Learning PHYSICS for IIT JEE

IIT JEE Physics - Home Page

2012-02-16T06:18:00.000-08:00

Study Plan,Revision and Quick Study Notes for Various Chapters
Chapters follow the sequence of Physics book by H.C. Verma

Chapters

1. Introduction to physics
Revision Notes
2. Physics and mathematics
Revision Notes
3. Rest and motion :kinematics
Study Guide and Revision Notes
4. The forces
Study Guide and Revision Notes
5. Newtons laws of motion
Study Guide and Revision Notes
6. Friction
Study Guide and Revision Notes
7. Circular motion
Study Guide and Revision Notes
8. Work and energy
Study Guide and Revision Notes
9. Centre of mass,linear momentum,collision
Study Guide and Revision Notes
10. Rotational mechanics
Study Guide and Revision Notes
11. Gravitation
Study Guide and Revision Notes
12. Simple harmonic motion
Study Guide and Revision Notes
13. Fluid mechanics
Study Guide and Revision Notes
14. Some mechanical properties of matter
Study Guide and Revision Notes
15. Wave motion and waves on a string
Study Guide and Revision Notes
16. Sound waves
Study Guide and Revision Notes
17. Light waves
Study Guide and Revision Notes
18. Geometrical optics
Study Guide and Revision Notes
19. Optical instruments
Study Guide and Revision Notes
20. Dispersion and spectra
Study Guide and Revision Notes
21. Speed of light
Study Guide and Revision Notes
22. Photometry

23. Heat and Temperature
Study Guide and Revision Notes
24. Kinetic theory of Gases
Study Guide and Revision Notes
25. Calorimetry
Study Guide and Revision Notes
26. Laws of Thermodynamics
Study Guide and Revision Notes
27. Specific Heat of Capacities of Gases
Study Guide and Revision Notes
28. Heat transfer
Study Guide and Revision Notes
29. Electric Field and Potential
Study Guide and Revision Notes
30. Gauss's Law
Study Guide and Revision Notes
31. Capacitors
Study Guide and Revision Notes
32. Electric Current in Conductors
Study Guide and Revision Notes

33. Thermal and Chemical Effects of Electric Current
Study Guide and Revision Notes
34. Magnetic Field
Study Guide and Revision Notes
35. Magnetic field due to a Current
Study Guide and Revision Notes
36. Permanent Magnets
Study Guide and Revision Notes
37. Magnetic Properties of Matter
Study Guide and Revision Notes
38. Electro Magnetic Induction
Study Guide and Revision Notes
39. Alternating current
Study Guide and Revision Notes
40. electromagnetic Waves
Study Guide and Revision Notes
41. Electric Current through Gases
Study Guide and Revision Notes
42. Photoelectric Effect and Wave-Particle Duality
Study Guide and Revision Notes
43. Bohr's Model and Physics of Atom
Study Guide and Revision Notes
44. X-Rays
Study Guide and Revision Notes
45. Semiconductors and Semiconductor Devices

46. Nucleus
Study Guide and Revision Notes
47. The Special Theory of Relativity

Newton's Law of Motion -Videos

2012-01-25T20:55:00.000-08:00

Videos are in collection

http://knol.google.com/k/narayana-rao/newton-s-law-of-motion/2utb2lsm2k7a/4496#

Friction - Videos

2012-01-25T20:53:00.000-08:00

Videos are in

http://knol.google.com/k/narayana-rao/friction-videos/2utb2lsm2k7a/4497#

Circular Motion - Videos - Physics Videos

2012-01-25T20:49:00.000-08:00

Videos are in

http://knol.google.com/k/narayana-rao/circular-motion-videos-physics-videos/2utb2lsm2k7a/4457#

Work and Energy - Videos

2012-01-25T20:48:00.000-08:00

Videos are in

http://knol.google.com/k/narayana-rao/work-and-energy-videos/2utb2lsm2k7a/4498#

Centre of mass - Linear momentum - Videos

2012-01-25T20:47:00.000-08:00

Videos are in

http://knol.google.com/k/narayana-rao/centre-of-mass-linear-momentum/2utb2lsm2k7a/4500#

Colliosions - Videos

2012-01-25T20:45:00.000-08:00

Videos are in

http://knol.google.com/k/narayana-rao/colliosions-videos/2utb2lsm2k7a/4501#

Rotational Mechanics - Videos

2012-01-25T20:44:00.000-08:00

Videos are in

http://knol.google.com/k/narayana-rao/rotational-mechanics-videos/2utb2lsm2k7a/4503#

Simple Harmonic Motion - Videos

2012-01-25T20:43:00.000-08:00

Video collection is in

http://knol.google.com/k/narayana-rao/simple-harmonic-motion-videos/2utb2lsm2k7a/4520#

http://knol.google.com/k/narayana-rao/rest-and-motion-kinematics-videos/2utb2lsm2k7a/4495

2012-01-25T20:42:00.001-08:00

Presently videos are in knol

http://knol.google.com/k/narayana-rao/rest-and-motion-kinematics-videos/2utb2lsm2k7a/4495

Mathematics for Physics - Videos

2012-01-25T20:39:00.000-08:00

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Tips for JEE 2012 Physics

2011-12-17T03:48:00.000-08:00

Visit Gyan Central forum post

Performance of the blog

2011-11-26T09:30:00.000-08:00

26 November 2011

Monthly page views 2150

Physics - Videos - Knol Book

2011-05-17T21:17:00.000-07:00

A knol book, collection of videos on various chapters of Physics was started on Google's Knol Platform.

The book now has many videos on various chapters. But now the videos are transferred to this blog only.

Heisenberg's Uncertainty Principle - Video Lecture

2011-04-24T00:34:00.000-07:00

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Crustal fragmentation -Rifting - Huge Oil Deposits in India

2010-03-26T00:38:00.000-07:00

In Herndon’s view, virtually all major geological activity is the consequence of a single process: Earth-crust fragmentation – splitting the Earth’s crust to form new surface area to accommodate decompression-increased planetary volume.
Crustal fragmentation, called rifting, provides all of the crucial components for petroleum-deposit formation: basin, reservoir, source, and seal. Rifting causes the formation of deep basins, as presently occurring in the Afar triangle of Northeastern Africa. Augmented by heat channeled upwards from deep within the Earth, uplift from sub-surface swelling can sequester sea-flooded lands to form halite evaporate deposits, lead to dome formation, and can make elevated land susceptible to erosion processes, thus providing sedimentary material for reservoir rock in-filling of basins. Moreover, crustal fragmentation potentially exposes deep basins to sources of abiotic mantle methane and, although still controversial, methane-derived hydrocarbons.

Drawing upon an understanding he developed with respect to the East African Rift System and the underlying rifting and extensive petroleum and natural gas deposits associated with the Siberian

Traps, Herndon predicts the extensively rifted region beneath the Deccan Traps of India will become the site of important energy-resource discoveries. In fact, the first discovery has already been reported.
For more information: http://www.NuclearPlanet.com/oil.html
For pdf of paper: http://www.NuclearPlanet.com/boost.pdf
Herndon, J. M. (2010) Impact of recent discoveries on petroleum and natural gas exploration: emphasis on India. Current Science, 98, 772-779.
Source:
J. Marvin Herndon, Ph.D.
Transdyne Corporation

For decades, an unsuspected geological blunder has limited crucial technical understanding of how, where and why petroleum and natural gas deposits form. Exposing and correcting that vital mistake offers the promise of new insights and potentially vast new energy-resource discoveries.
Since the 1930s, the idea of mantle convection has been inextricably rooted in common geological interpretations of Earth’s dynamics. In a paper just published in the March 25, 2010, issue of Current Science, San Diego geophysicist J. Marvin Herndon of Transdyne Corporation discloses a very serious problem with the prevailing concept of convection in the Earth’s mantle and reveals the profound implications on oil and gas exploration.
For decades geologists and geophysicists have assumed that convection occurs within the Earth’s mantle. But according to Herndon’s discovery, Earth-mantle convection is physically impossible. As he explains in his paper, the mantle is compressed by its own weight and the weight of the crust, so that its bottom is about 62% more dense than the top. The negligible amount of thermal expansion that might occur at the bottom, less than 1%, cannot cause bottom-mantle matter to float to the surface or make the mantle top-heavy, necessary conditions for convection.

Herndon’s discovery has revolutionary implications for geologists, who have for decades misapplied mathematical convection-justification relationships to the gravity-compressed mantle; such relationships are only valid for incompressible fluids.
Familiar topical names, such as Pangaea, Gondwanaland and Plate Tectonics, will begin to fade into history, replaced by a more correct 21st Century understanding of geology and geodynamics without mantle convection.

Source: A relealse from Mr. Herndon

Avogadro and His Constant

2010-03-11T20:11:00.000-08:00

Read an intersting account of the development of Avogadro's constant in a 16 page article.

http://www.sussex.ac.uk/chemistry/documents/the_constant_of_avogadro.pdf

The interseting point in the article is the paragraph.

Our current interpretation of gas structure has its origins in a chapter in the book
‘Hydrodynamik’ by Bernoulli, published in 1738, but this work was overlooked for
more than a hundred years. Also, in 1845 J.J.Waterston, a school teacher in Bombay,
submitted a paper to the Royal Society with the title ‘On the physics of media
composed of free and perfectly elastic molecules in a state of motion’, in which many
of the currently accepted concepts of kinetic theory were set out. Unfortunately this
paper was rejected by the society as “nothing but nonsense, unfit even for reading
before the society”. However, the manuscript was rediscovered in the archives by
Lord Rayleigh who deduced that it was essentially correct, and the paper was
published in the Philosophical Transactions in 1892 (15). Rayleigh wrote a preamble
to the paper describing its treatment, in which he says that the referee of Waterston’s
paper was one of the best qualified authorities of the day, and that the failure to
publish the paper probably held back the subject by 10 to 15 years. In the meantime
there had been major developments of the theory, particularly by Clausius, Maxwell,
and Boltzmann.

I came to know of Mr. Waterston from a talk delivered by Dr. M. Bama, director of TIFR on 10.3.2010 on the occasion of Foundation day of IIT Bombay.

IIT JEE 2009 Physics Paper II Question Paper Topics

2010-02-07T00:29:00.000-08:00

1. Photoelectric effect I-V graph

2. Velocity acceleration

3. Frequency of oscillation of a spring

4. Oscillation of a spring

5. Charge moving in an elliptical orbital - Angular movement variables

6. Rolling motion of a sphere. Velocities at various points.

7. Thermal cycle - Processes of the cycle and work during various processes

8. Resonance air column method - Measuring speed of sound in air

9. Force induced in a solenoid

10. What happens in these processes of systems?

(p) System : A capacitor, initially uncharged

Process : It is connected to a battery

(q) System : A gas in an adiabatic container fitted with an adiabatic piston

Process : The gas is compressed by pushing the piston

(r) System : A gas in a rigid container

Process : The gas gets cooled due to colder atmosphere surrounding it

(s) System : A heavy nucleus, initially at rest

Process : The nucleus fissions into two fragments of nearly equal masses and some neutrons are emitted

(t) System : A resistive wire loop

Process : The loop is placed in a time varying magnetic field perpendicular to its plane

Matching alternatives provided

(A) The energy of the system is increased

(B) Mechanical energy is provided to the system, which is converted into energy of random motion of its parts

(D) Mass of the system is decreased

11. Young's Double slit experiment with screen at various places

12. Charge inside a sphere

13. Current through a triangular wireloop and magentic field due to it.

14. Combination of elastic and inelastic collisions

15. Surface tension - soap bubble

16. simple pulley work done

17. Water coming out of an orifice of a sealed vessel kept in water. How much water will go out?

18. Vibrations of a string

19. Conduction of heat through a rod

Topics Asked in IIT JEE 2009 Examination in Physics - Paper I

2010-02-02T07:09:00.000-08:00

Specific Topic Asked in IIT JEE 2009 Examination in Physics - Paper I

1. Static coefficient of friction and inclined plane.

A block of base 10 cm × 10 cm and height 15 cm is kept on an inclined plane. The

coefficient of friction between them is square root of 3 . The inclination θ of this inclined plane from

the horizontal plane is gradually increased from 0º. Then

(A) at θ = 30º, the block will start sliding down the plane

(B) the block will remain at rest on the plane up to certain θ and then it will topple

angles

(D) at θ = 60º, the block will start sliding down the plane and on further increasing θ, it

will topple at certain θ

Answer; B

2. Simple harmonic motion graph and acceleration of the particle at an instant in time.

3. Spherical shell, Electric Charges and Charge densities

4. Electric flux on a specified surface due to multiple charges of various types: Point, wire, disc,

5. A system of bodies of different shapes with specified masses: Finding the centre of mass of system of bodies.

6. Wire body or frame in a magnetic field. Direction of current and amount of current to be specified.

7. Problem of apparent speed when somebody watches from under the water above.

8. Collisions between particles on a circular path.

9. Current and voltage in electric circuit of resistors.

10. Question on inertial frame

If the resultant of all the external forces acting on a system of particles is zero, then from

an inertial frame, one can surely say that

(A) linear momentum of the system does not change in time

(B) kinetic energy of the system does not change in time

(D) potential energy of the system does not change in time

Answer: A

11. Errors in measurements

A student performed the experiment of determination of focal length of a concave mirror

by u-v method using an optical bench of length 1.5 meter. The focal length of the mirror

used is 24 cm. The maximum error in the location of the image can be 0.2 cm. The 5 sets

of (u, v) values recorded by the student (in cm) are : (42, 56), (48, 48), (60, 40), (66, 33),

(78, 39). The data set(s) that cannot come from experiment and is(are) incorrectly

recorded, is (are)

(A) (42, 56) (B) (48, 48) (C) (66, 33) (D) (78, 39)

Answer. C, D

12. Cv and Cp, the molar specific heat capacities of a gas at constant volume and

constant pressure for monoatomic gas and diatomic gas

(A) Cp – Cv is larger for a diatomic ideal gas than for a monoatomic ideal gas

(B) Cp + Cv is larger for a diatomic ideal gas than for a monoatomic ideal gas

(D) Cp . Cv is larger for a diatomic ideal gas than for a monoatomic ideal gas

Answer: B, D

13. Fusion reactor and Lawson Number

14. Standing waves and de Broglie relation.

15. Arrangement of six point charges. Various properties.

16. Velocity and acceleration of bodies in various arrangements

Hubble Space Telescope - A Knol Useful to Know More about Optical Instruments

2009-07-31T02:11:00.000-07:00

Selected Passages from the Article about Hubble Telescope

The Hubble Space Telescope was launched in 1990, a joint project of NASA (the National Aeronautics and Space Administration of the United States) and ESA (the European Space Agency). It carries a 2.4-m (94-inch) telescope that feeds several different instruments. It is in low Earth orbit, allowing it to be reached and serviced by astronauts, a process that made it work properly in the first place and that continues to allow its updating.

History of Hubble
The Hubble Space Telescope is the descendant of a planned Large Space Telescope, but during the 1980's it was downsized in planning both for psychological reasons, so the word "Large" wouldn't go in the proposal to Congress, and to allow it to fit in the payload bay of a space shuttle. Lyman Spitzer of Princeton University and John Bahcall of the Institute for Advanced Study, also located in Princeton, were principal scientists who worked not only scientifically but also politically to see the project advance.

The mirror was made by the Perkin-Elmer Company in Connecticut, and was said to be the most perfectly and smoothly shaped telescope mirror ever. The telescope mirror was completed and the telescope almost ready to be launched when the space-shuttle Challenger exploded in 1984. With space-shuttle launches suspended, the telescope was put into storage.

For diagrams please visit the source knol.

The telescope was launched on April 24, 1990, from Cape Canaveral on a space shuttle. It was named after Edwin P. Hubble, the astronomer at the Palomar Observatory who had discovered the important cosmological law about the expansion of the Universe, linking its rate of expansion linearly with distance. It received the name in recognition of the prospectively important cosmological work the telescope could do, and in the hope that it could refine Hubble's Law—in particular, Hubble's constant, the constant of proportionality between redshift and distance—to a higher accuracy than had been previously possible.

Science with Hubble
The Hubble Space Telescope has been used by astronomers to study objects in the Universe near and far, excepting only the Sun (which is too bright, but which was indeed detected through the back of the mirror!). A main reason for the launch of Hubble is that from its perch outside Earth's atmosphere, it can have resolution about 7 times finer than normal ground-based resolution from good telescope sites; that is, it can see detail about 7 times finer. It had often been loosely said that it could therefore see 7 times farther into space, but large ground-based telescopes had already been observing objects so far in the outer solar system that it was impossible to see 7 times farther.

In the years since Hubble's launch, ground-based capabilities have advanced, and Active Optics has allowed Hubble's resolution to be achieved in certain limited but growing circumstances from ground-based telescopes. Still, Hubble can attain its high resolution for all objects it observes without complicated post-processing.

Note, however, that Hubble is only one 2.4-m telescope, not large by today's standards. The twin Keck telescopes in Hawaii, for example, have mirrors each 10 m in diameter, about 4 times in diameter and 16 times in area compared with Hubble's. Thus many astronomical projects, particularly those that require collecting as much light as possible, are better carried out with this new generation of large, mountain-based telescopes, still leaving many, many projects best achieved with the high-resolution of Hubble.

Source
Hubble Space Telescope By Jay M. Pasachoff, Astronomer,Williams College, Williamstown, MA, and Chair of the International Astronomical Union's Working Group on Solar Eclipses

http://knol.google.com/k/jay-m-pasachoff/hubble-space-telescope/2vj7b2e7cti8y/1

The knol is under Creative Commons Attribution 3.0 License on 31.7.2009

You can also visit

http://hubblesite.org

Want to know more about music - Piano Chords

2009-07-31T01:41:00.001-07:00

Piano Chords -- How They Are Formed & How They WorkChords: The Harmonic Background Of Melody

A chord is any group of 3 or more notes that are played at the same time. Broken chords, also known as arpeggios, are chords which are played one note at a time, but add up to 3 or more notes.

Chords are made from scales.

A scale is simply a row of notes in some consistent pattern. The word “scale” comes from a Latin word meaning “ladder” – notes ascend or descend the ladder rung by rung.

The notes of all 12 major scales according to their position in the scale is given as a diagram in the knol

http://knol.google.com/k/duane-shinn/piano-chords-how-they-are-formed-how/189kon8274mv1/3#

Visit the article to know more about Piano Chords

Knol is available on Creative Commons Attribution 3.0 License on 31.7.2009

Sound and its measurement

2009-07-31T01:31:00.000-07:00

NATURE OF SOUND

Origin of sound
Sound is a variation in the pressure of the air of a type which has an effect on our ears and brain. These pressure variations transfer energy from a source of vibration that can be naturally-occurring, such as by the wind or produced by humans such as by speech. Sound in the air can be caused by a variety of vibrations, such as the following.

Moving objects: examples include loudspeakers, guitar strings, vibrating walls and human vocal chords.
Moving air: examples include horns, organ pipes, mechanical fans and jet engines.
A vibrating object compresses adjacent particles of air as it moves in one direction and leaves the particles of air ‘spread out’ as it moves in the other direction. The displaced particles pass on their extra energy and a pattern of compressions and rarefactions travels out from the source, while the individual particles return to their original positions.

In addition to its link with human hearing the term sound is also used for other movement in air governed by similar physical principles. Disturbances in the air with frequencies of vibration which are too low (infrasound) or too high (ultrasound) to be heard by human hearing are also regarded as sound. Other sound terms in common usage include: underwater sound, sound in solids, or structure-borne sound.

Infrasound: frequency too low for human hearing
Ultrasound: frequency too high for human hearing

Wave motion
The mechanical vibrations of sound move forward using wave motion. This means that, although the individual particles of material such as air molecules return to their original position, the sound energy obviously travels forward. The front of the wave spreads out equally in all directions unless it is affected by an object or by another material in its path. The sound waves can travel through solids, liquids and gases, but not through a vacuum.

It is difficult to depict a longitudinal wave in a diagram so it is often convenient to represent a sound waves as a plot against time of the vibrations. The vibrations can be throught of as the movements of the souce of sound, such as a vibrating loudspeaker, or as the movements of a particle of air. For a pure sound of one frequency, as shown, the plot takes the smooth and regular form of a sine wave.

For diagram visit the source

Sound waves are like any other wave motion and therefore can be specified in terms of wavelength, frequency and velocity.

Wavelength
Wavelength (l) is the distance between any two repeating points on a wave. The unit is the metre (m)

Frequency
Frequency (f) is the number of cycles of vibration per second. The unit is the hertz (Hz)

Velocity
Velocity (v) is the distance moved per second in a fixed direction. The unit is metres per second (m/s)

For every vibration of the sound source the wave moves forward by one wavelength. The length of one wavelength multiplied by the number of vibrations per second therefore gives the total length the wave motion moves in 1 second. This total length per second is also the velocity. This relationship between velocity, frequency and wavelength is true for all wave motions and can be written as the formula.

n =f ´ l

where v = velocity in m/s

f = frequency in Hz

l = wavelength in m

The velocity of sound, for any particular material, stays constant. Therefore any increase in freqency, for example, is matched by a decrease in wavelength.

Velocity of sound
A sound wave travels away from its source with a speed of 344 m/s (770 miles per hour) when measured in dry air at 20 °C (68 °F) . This is a respectable speed within a room but slow enough over the ground for us to notice the delay between seeing a source of sound, such as a distant firework, and later hearing the explosion.

The velocity of sound is independent of the rate at which the sound vibrations occur, which means that the frequency of a sound does not affect its speed. The velocity is also unaffected by variations in atmospheric pressure such as those caused by the weather.

But the velocity of sound is affected by the properties of the material through which it is travelling, and the table gives an indication of the velocities of sound in different materials.

The velocity of sound in gases decreases with increasing density as, when the molecules are heavier, then they move less readily. Moist air contains a greater number of light molecules and therefore sound travels slightly faster in moist humid air.

Sound travels faster in liquids and solids than it does in air because of the effect of density and elasticity of those materials. The particles of such materials respond to vibrations more quickly and so convey the pressure vibrations at a faster rate. For example, steel is very elastic and sound travels through steel about 14 times faster than it does through air.

Table of Velocity of sound
Material
Typical velocity (m/s)

Air (0°C)
331

Air (20°C)
344

Water (25°C)
1498

Pine
3300

Glass
5000

Steel
5000

Granite
6000

Frequency of sound
If an object that produces sound waves vibrates 100 times a second, for example, then the frequency of that sound wave will be 100 Hz. The human ear hears this as sound of a certain pitch.

Pitch is the frequency of a sound as perceived by human hearing.
Low-pitched notes are caused by low-frequency sound waves and high-pitched notes are caused by high-frequency waves. The pitch of a note determines its position in the musical scale. The frequency range to which the human ear responds is approximately 20 to 20 000 Hz and frequencies of some typical sounds are shown in the figure.

‘bass’ = low frequency
‘treble’ = high frequency
Most sounds contain a combination of many different frequencies and it is usually convenient to measure and analyse them in ranges of frequencies, such as the octave.

An Octave Band is the range of frequencies between any one frequency and double that frequency.
Quality of sound
A pure tone is sound of only one frequency, such as that given by a tuning fork or electronic signal generator. Most sounds heard in everyday life are a mixture of more than one frequency, although a lowest fundamental frequency predominates when a particular ‘note’ is recognisable. This fundamental frequency is accompanied by overtones or harmonics.

Overtones and Harmonics are frequencies equal to whole-number multiples of the fundamental frequency.
For example, the initial overtones of the note with a fundamental of 440 Hertz are as follows:

440 Hz = fundamental or 1st harmonic

880 Hz = 1st overtone or 2nd harmonic

1320 Hz = 2nd overtone or 3rd harmonic etc.

Different voices and instruments are recognised as having a different quality when making the same note. This individual timbre results because different instruments produce different mixtures of overtones that accompany the fundamental. The frequencies of these overtones may well rise to 10 000 Hz or more and their presence is often an important factor in the overall effect of a sound. A telephone, for example, transmits few frequencies above 3000 Hz and the exclusion of the higher overtones noticeably affects reproduction of the voice and of music.

Cancellation of sound
The nature of a sound wave, such as shown in the earlier figure, means that the vibration of the wave has alternate changes in amplitude called phases. If a wave vibration in one direction meets an equal and opposite vibration, then they will cancel. The effect of this phase inversion in sound waves is to produce little or no sound and gives the possibility of ‘cancelling’ noise. This is the principle of Active Noise Reduction (ANR) used in some headsets and aircraft for example.

Resonance
Every object has a natural frequency which is the characteristic frequency at which it tends to vibrate when disturbed. For example, the sound of a metal bar dropped on the floor can be distinguished from a block of wood dropped in the same way. The natural frequency depends upon factors such as the shape, density and stiffness of the object.

Resonance occurs when the natural frequency of an object coincides with the frequency of any vibrations applied to the object. The result of resonance is extra large vibrations at this frequency.

Resonance may occur in many mechanical systems. For instance, it can cause loose parts of a car to rattle at certain speeds when they resonate with the engine vibrations. The swaying of a suspension bridge can resonate with footsteps from walkers. The shattering of a drinking glass has been attributed to resonance of the object with a singer’s top note! Less dramatic, but of practical application in buildings, is that resonance affects the transmission and absorption of sound within partitions and cavities.

MEASUREMENT OF SOUND

Decibels
The uneven sensitivities of the human hearing system lead us to measuring sound by a logarithmic decibel scale which is progressively 'squashed' rather than being a uniform scale. It happens that this is also the way that our hearing perceives sound energy or strength. So the simple energy or pressure measurements of sound are converted to sound level values in decibels (dB) which are easier numbers for humans to understand and relate to. Extra-terrestrial beings, or even your cat, might well prefer the unconverted values!

Sound levels in decibels start with a zero at the threshold of hearing which is the weakest sound that the average human ear can detect Typical effects of sound levels and changes in sound levels are shown in the illustrations. Remember that there is distinct difference between a change in energy and a change in our idea of loudness.

A change in sound level of + or - 10 dB is a useful figure to remember as it makes difference of approximately twice as loud, or half as loud. We have to say 'approximately' as the experience also depends on individual hearing, on the background noise and on the exact frequencies involved. An increase in sound level of 20 dB (10 dB then another 10 dB) will seem four times

For example, there may be a proposal to increase the average sound level of your environment from 60 dB to 70 dB. This seems a relatively small change, after all the scale runs from 0 to 140 but it will make the environment twice as noisy.

The same idea applies to reducing noise. If the manufacturers of a certain machine can reduce the sound level from 90 dB to 80 dB then the machine will sound approximately half as loud as before.

For Table of Decibel scale visit the source

Sound Meters are also explained in the source article in knol.

Visit the source for diagrams and updated versions.

Source:

Sound and its measurement, Randall McMullan
http://knol.google.com/k/randall-mcmullan/sound-and-its-measurement/1hvmbypv7oiib/3#

The article is in Creative Commons Attribution 3.0 License on 31.7.2009

Interesting Articles on Physics for Dowload

2009-07-18T21:28:00.000-07:00

http://knol.google.com/k/narayana-rao-kvss/knol-sub-directory-physics-interesting/2utb2lsm2k7a/1446#

A list of articles for study and download.
You can search for more articles on knol.

IIT JEE 2011 Physics Study Diary - Ch.4 Forces Day 3

2009-05-26T06:20:00.000-07:00

Day 3

4.4 Nuclear Forces
4.5 Weak forces
4.6 Scope of Classical physics

Points to be Noted

Nuclear forces

The alpha particle is a bare nucleus of Helium. It contains two protons and two neutrons. It is a stable object and once created it can remain intact until it is not made to interact with other objects.

The protons in the nucleus will repel each other due to coulomb force and try to break the nucleus. Why does the Coulomb force fail to break the nucleus?

There are forces called nuclear forces and they are exerted only if the interacting particles are protons or neutrons or both. They are largely attractive, but with a short range. They are weaker than the Coulomb force if the separation between particles is more than 10^-14 m. For separation smaller than this the nuclear force is stronger than the Coulomb force and it holds the nucleus stable.

Radioactivity, nuclear energy (fission, fusion) etc. result from nuclear force.

Weak forces

A neutron can change into proton and simultaneously emit an electron and a particle called antinutrino.

A proton can also change into neutron and simultaneously emit a positron (and a neutrino). The forces responsible for these changes are called weak forces. The effect of this force is experienced inside protons and neutrons only.

Scope of classical physics

Physics based on Newton's Laws of motion, Newton's law of gravitation, Maxwell's electromagnetism, laws of thermodynamics and the Lorentz force is called classical physics. The behaviour of all the bodies of linear sizes greater than 10^-6 m are adequately described by classical physics. Grains of sands and rain drops fall into this range as well as heavenly bodies.

But sub atomic particles like atoms, nuclei, and electrons have sizes smaller than 10^-6 m and they are explained by quantum physics.

The mechanics of particles moving at velocity equal to light are explained by relativistic mechanics formulated by Einstein in 1905.

IIT JEE Physics Study Diary - Ch.3 Forces - Day 2

2009-05-25T11:45:00.000-07:00

Day 2
4.3 Electromagnetic (EM) forces
Ex. 4.1

Points to note

Electromagnetic force

Apart from gravitational force between any two bodies, the particles may exert upon each other electromagnetic forces.

If two particles having charges q1 and q2 are at rest with respect to the observer, the force between them has a magnitude

F = (1/4πε0)(q1q2/r^2)

Where ε0 = permittivity of air or vacuum = 8.8549 x 10^-12 C² /N-m²
The quantity (1/4πε0) = 9.0 x 10^9 N-m² /C²

q1, q2 = charges
r distance between q1 and q2

This is called coulomb force and it acts along the line joining the particles.

Atoms are composed of electrons, protons and neutrons.

Each electron has 1.6*10^-19 coulomb of negative charge. Each proton has an equal amount of positive charge.

In atoms, the electrons are bound by the electromagnetic force exerted on them by charge on protons. Even the combination of atoms in molecules are brought about by electromagnetic forces only. A lot of atomic and molecular phenomena result from electromagnetic forces between subatomic particles (for example, theory is put forward that charged mesons are responsible for the stability of nucleus).

Examples of electromagnetic force:

1. Bodies in contact: The contact force between bodies in contact arises out of electromagnetic forces acting between the atoms and molecules of the surfaces of the two bodies. The contact force may have a component parallel to the contact surface. This component is known as friction.

2. Tension in a string: Tension in the string is due to electromagnetic forces between atoms or electrons and protons (free electrons and nucleus in metals).

3. Force due to spring: If a spring has natural length x0 and if it is extended to x, it will exert a force

F = k|x-x0| = k|∆x|

k, the proportionality constant is called the spring constant. This force comes into picture due to the electromagnetic forces between the atoms of the material.

Formulas in the session

F = (1/4πε0)(q1q2/r^2)

Where ε0 = permittivity of air or vacuum = 8.8549 x 10^-12 C² /N-m²
The quantity (1/4πε0) = 9.0 x 10^9 N-m² /C²

q1, q2 = charges
r distance between q1 and q2

Each electron has 1.6*10^-19 coulomb of negative charge. Each proton has an equal amount of positive charge.

Force due to spring: If a spring has natural length x0 and if it is extended to x, it will exert a force

F = k|x-x0| = k|∆x|

k, the proportionality constant is called the spring constant.

Physics Study Diary - Ch. 4 Forces - Day 1

2009-05-23T17:39:00.000-07:00

Day 1 Study Plan

4.1 Introduction
4.2 Gravitational forces

Points to Note

Force

Force is an interaction between two objects.
Force is exerted by an object A on another object B.
Force is a vector quantity. Hence if two or more forces act on a particle, we can find the resultant force using laws of vector addition.

The SI unit for measuring the force is called a newton.

Newton's third law of motion

If a body A exerts a force F on another body B, then B exerts a force -F on A,the two forces acting along the same line.

Gravitational force

Any two bodies attract each other by virtue of their masses.

The force of attraction between two point masses is

F = Gm1m2/r²
where m1 and m2 are the masses of the particles and r is the distance between them.

G is a universal constant having the value 6.67 x 10^-11 N-m²/kg²

The above rule was given for point masses. But it is analytically found that the gravitational force exerted by a spherically symmetric body of mass m1 on another such body of mass m2 kept outside the first body is Gm1m2/r² where r is the distance between the centres of such bodies.

Thus, for the calculation of gravitational force between two spherically symmetric bodies, they can be treated as point masses placed at their centres.

Gravitational force on small bodies by the earth

For earth, the value of radius R and mass M are 6400 km and 6 x 10^24 kg respectively. Hence, the force exerted by earth on a particle of mass m kept at its surface is, F = GMm/R². The direction of this force is towards the centre of the earth.

The quantity GM/R² is a constant and has the dimensions of acceleration.
It is called acceleration due to gravity and is denoted by letter g.
Hence, g and G are different.

Value of g is approximately 9.8 m/s².
In calculations, we often use 10 m/s².

Force exerted on a small body of mass m, kept near the earth's surface is mg in the vertically downward direction.

Gravitational constant is so small that the gravitational force becomes appreciable only when one of the masses has a very large mass.

HC Verma gives the example of Force exerted by a body of 10 kg on another body of 10 kg when they are separted by a distance of 0.5 m. The force comes out to be 2.7*10^-8 N which can hold only 3 microgram. Such forces can be neglected in practice.
Hence we consider only gravitational force exerted by earth.

Formulas

1. F = Gm1m2/r²
where m1 and m2 are the masses of the particles and r is the distance between them.

G is a universal constant having the value 6.67 x 10^-11 N-m²/kg²

2. Force exerted by earth on a particle of mass m kept at its surface is, F = gm/R².

g = approximately 9.8 m/s².
In calculations, we often use 10 m/s²

IIT JEE 2011 Physics Study Diary - Ch.3 Rest and Motion - Day 5

2009-05-22T22:01:00.000-07:00

Rest and Motion
Day 5 study plan

3.9 Change of frame
Ex. 3.10, 3.11
WOE 16,17, 18

Points to Note

The main theme of the section is expressing velocity w.r.t. one Frame into velocity w.r.t. to a different frame

If XOY is one frame called S and X'O'Y' is another frame called S' we can express velocity of a body B w.r.t. S as a combination of velocity of body w.r.t. to S' and velocity of S' w.r.t to S.

V(B,S) = V(B,S')+V(S',S)

Where
V(B,S) = velocity of body w.r.t to S
V(B,S') = velocity of body w.r.t to S'
V(S',S) = velocity of S' w.r.t to S

we can rewrite above equation as

V(B,S') = V(B,S)- V(S',S)

We can interpret the above equation in terms of two bodies. Assume S', and B are two bodies. If we know velocities of two bodies with respect to a common frame (in this case S)we can find the velocity of one body with respect to the other body (V(B,S')

The above expressions for velocity were derived from the relation between position vectors of the body w.r.t. to S and S' and position vector of origin of S' with respect to origin of S.

r(B,S) = r(B,S')+r(S',S)

Differentiating the position vectors with respect to gives respective velocity

Formulas covered in the session

26. r(B,S) = r(B,S')+r(S',S)

Where

r(B,S) = Position vector
r(B,S') = Position vector
r(S',S) = Position vector

27. V(B,S) = V(B,S')+V(S',S)

Where
V(B,S) = velocity of body wrt to S)
V(B,S') = velocity of body wrt to S')
V(S',S) = velocity of S' wrt to S)

we can rewrite above equation as

28. V(B,S') = V(B,S)- V(S',S)

IIT JEE 2011 Physics Study Diary - Ch.3 Rest and Motion - Day 4

2009-05-21T08:29:00.001-07:00

Day 4 - Study Plan

3.7 Motion in a plane
Ex. 3.8
3.8 Projectile motion
Ex. 3.9
WOE 11,12, 14

Points to Note

Motion in a plane

Motion in plane is described by x coordinate and y coordinate, if we choose X-Y plane. You can imagine time t is on the third axis.

The position of the particle or the body can be described by x and y coordinates.

r = xi = yj

Displacement during time period t to t+Δt can be represented by Δr

Δr = Δxi = Δyj

Then Δr/Δt = (Δx/Δt)i = (Δy/Δt)j

Taking the limits as Δt tends to zero

v = dr/dt = (dx/dt)i+(dy/dt)j ... (3.15)

Hence x component of velocity is dx/dt

The x-coordinate, the x component of velocity, and the x component of acceleration are related by equations of straight line motion along X axis.
Similarly y components.

Projectile

Projectile motion is an important example of motion in a plane.

What is a projectile? When a particle is thrown obliquely near the earth's surface, it is called a projectile. It moves along a curved path. If we assume the particle is close to the earth and negligible air resistance to the motion of the particle, the acceleration of the particle will be constant. We solve projectile problems with the assumption that acceleration is constant.

Vertical motion of the projectile is the motion along Y axis and horizontal motion is motion along X axis.

Terms used in describing projectile motion

Point of projection
Angle of projection
Horizontal range
Time of flight
Maximum height reached

The motion of projectile can be discussed separately for the horizontal and vertical parts.

The origin is taken as the point of projection.
The instant the particle is projected is taken as t = 0.
X-Y plane is the plane of motion.
The horizontal line OX is taken as the X axis.
Vertical line OY is the Y axis.
Vertically upward direction is taken as positive direction of Y

Initial velocity of the particle = u
Angle between the velocity and horizontal axis = θ

ux – x-component of velocity = u cos θ
ax – x component of acceleration = 0

uy – y component of velocity = u sin θ
ay = y component of acceleration = -g

Horizontal motion of the projectile – Equations of motion

ux = u cos θ
ax = 0
vx = ux +axt = ux = u cos θ (as ax = 0)
Hence x component of the velocity remains constant.
Displacement in horizontal direction = x = uxt+1/2ax t²
As ax = 0, x = ux t = ut cos θ

Vertical motion – Equations of motion
uy = u sin θ
ay = -g
vy = uy – gt
Displacement in y direction = y = uyt – ½ gt²
vy² = uy² - 2gy

22. Time of flight of the projectile = (2u sin θ)/g

23. OB = (u²sin 2θ)/g

24. t = (u sin θ)/g
At t vertical component of velocity is zero.

25. Maximum height reached by the projectile = (u² sin²θ)/2g

IIT JEE Physics Study Diary - Ch.3 Rest and Motion - Day 3

2009-05-20T20:48:00.000-07:00

Day 3 Study Plan

3.6 Motion in a straight line
Ex. 3.5.3.6, 3.7
WOE 3,4,5,6,

Points to Note

Motion in a straight line

As the motion is constrained to move on a straight line, choose the straight line in which motion is taking place as X-axis. Hence x represent the position of the particle at any time instant t. If you want you can imagine a graph between t and x but now t in on the vertical axis and x is on the horizontal axis.

Generally origin is taken at the point where the particle is situated at time t = 0.

Position of the particle at time t is given by x and also x measures displacement (not distance).
Velocity is v = dx/dt (3.9)
acceleration is a = dv/dt (3.10)
a = d²x/dt² (3.11)

Decelaration

If acceleration is negative, then it is along the negative X-axis. It is called deceleration

Motion with constant acceleration

Using integration the formulas for v velocity at any instant, x position at any instant and relation between v,u,x and a are derived in this section.

If acceleration is constant dv/dt = a (constant)
initial velocity = u (at time t =0)
final velocity = v (at time t)
Then v = u+at (3.12)

x = distance moved in time t = ut+½at² (3.13)

Also v² = u²+2ax (3.14)

u,v, and a as well as may take negative or positive values. When u, v and a are negative it shows velocity or acceleration is in the negative X direction.

Example 3.5
a) The question asked is distance travelled. The expression for x gives only displacement. But the remark is that as the particle does not turn back it is equal to distance travelled. Be careful when initial velocity is positive and the acceleration is negative.

Example 3.6
There was a past JEE question which is based on the variable defined in the example.

Freely falling bodies

In this case take the Y axis as the straight line on which the particle or body is moving.

You can take height above the ground as +y and work out the problems.

You can take the starting position of the body as the origin and work out the problem.
The choice may be yours or some choice may be more appropriate in case of some problems, be clear of the formula that you have to use depending on the choice you made.

g is approximately equal to 9.8 m/s², but for convenience in many problems it is given as 10m/s².

Physics Study Diary for IIT JEE - Ch.3 Rest and Motion - Day 2

2009-05-20T02:15:00.000-07:00

Plan for Day 2

4. Average velocity and instantaneous velocity
Ex. 3.4
Worked out example 2
3.5 Average accleration and instantaneous aceleration
WOE 3 to 4

Exercises: 1 to 5

Points to Note

Average velocity

Average speed and average velocity of a body over a specified time interval may not turnout to be same.

Example See the worked out example 2 of HC Verma's book.
The teacher made 10 rounds back and forth in the room and the total distance moved is 800 feet (10 rounds back and forth of 40 ft room). As the time taken is 50 minutes, average speed is 800/50 = 16ft/min.
But because he went out of the same door that he has entered, displacement is zero and hence average velocity is zero.

Instantaneous velocity

Average acceleration

Instantaneous acceleration

Position Vector: If we join the origin to the position of a particle by a straight line and put an arrow towards the position of the particle, we get the position vector of the particle.

If the particle moves from position A to position B, we can define position vector of A and position vector of B and OB - OA will give displacement ( a vector quantity).

Another point to note: slope of velocity-time diagram gives the instant acceleration at that point.

Physics Study Diary for IIT JEE 2011 - Ch.3 Rest and Motion

2009-05-18T20:27:00.000-07:00

I am planning to study the Physics chapters as per the study plan that I have given. This study would be of help to me in preparing JEE Level Revision problem set for each chapter.

Today (19.5.2009) I did the following portion

Day 1

3.1 Rest and Motion
3.2 Distance and displacement
Ex. 3.1
3.3 average speed and instantaneous speed
Ex. 3.2,3.3
Worked out examples 1,2

Points to note.

3.1 Rest and Motion

Motion is a combined property of the object under study and the observer. There is no meaning of rest or motion without the viewer.

To identify the rest or motion, we need to locate the position of a particle with respect to a frame of reference. The frame of reference will have three mutually perpendicular axes (X-Y-Z) and the particle can be represented by coordinates x,y,z.
If all coordinates remain unchanged as time passes, we say that particle is at rest. If there is change in any of the coordinates with time, we say the particle or the body represented by the particle is having motion.

I some problems or situations frame of reference is specifically mentioned. Otherwise the frame of reference is understood more easily from the context.

Figure 1: A man with a pistol threatening and asking people not to move.

3.2 Distance and Displacement

If a particle moves from position A to Position B in time t, displacement is the length of the straight line joining A to B. The direction of a vector representing this displacement is from A to B. Displacement is a vector quantity. It has both magnitude and direction.

In the movement between positions A and B the particle may take the path ACB. The length of the path ACB will be distance travelled by the particle. It is only scalar quantity. It has not direction.

3.3 Average speed and Instantaneous speed

The average speed of a particle in a specific time interval is defined as the distance travelled by the particle divided by the time interval.

We can plot the distance s as a function of time. In this graph, the instantaneous speed at time t equals the slope of the tangent at the time t. The average speed in a time interval t to t+Δt become equal to the slope of the chord Δs/Δt. As Δt becomes approaches zero, this average speed becomes instantaneous speed and ds/dt becomes the instantaneous speed.

If we plot a speed versus time graph ( v versus t), the distance travelled in time t (t1 to t2) will be equal to the area bounded by the curve v = f(t), x axis, and the two ordinates t = t1 and t = t2.

In terms of integration it can be represented as s = ∫vdt from t1 to t2

For study plan for IIT JEE 2011 for the year 2009-10

http://iit-jee-2011.blogspot.com/2009/04/it-jee-2011-annual-study-plan-for.html

Nobel Prize Winners in Physics from 1901-1925 - IIT JEE - Extra-curricular Study

2009-05-18T20:14:00.001-07:00

Year Physics

1901 Röntgen, Wilhelm Conrad
For discovery of X-rays

1902 Lorentz, Hendrik A.
Zeeman, Pieter

1903 Becquerel, Henri;
Curie, Pierre;
Curie, Marie
1904 Rayleigh, Lord

1905 Lenard, Philipp
1906 Thomson, J. J.

1907 Michelson, Albert A.

1908 Lippmann, Gabriel

1909 Braun, Ferdinand
Marconi, Guglielmo
1910 van der Waals, Johannes Diderik
1911 Wien, Wilhelm

1912 Dalén, Gustaf

1913 Onnes, Heike Kamerlingh
1914 von Laue, Max
1915 Bragg, William Henry:
Bragg, William Lawrence
1916 None
1917 Barkla, Charles Glover

1918 Planck, Max
1919 Stark, Johannes
1920 Guillaume, Charles Edouard
1921 Einstein, Albert

1922 Bohr, Niels

1923 Millikan, Robert A.

1924 Siegbahn, Manne
1925 Franck, James
Hertz, Gustav

Sources

http://nobelprize.org/nobel_prizes/physics/laureates/http://history1900s.about.com/library/misc/blnobelphysics.htm

Noble Prize Winners in Physics from 2001 - IIT JEE - Extra-curricular Study

2009-05-15T08:18:00.000-07:00

Year - Scientist/Physicist

2001 - Eric A. Cornell, Carl E. Wieman, (US), Wolfgang Ketterle (Germany)

2002 - Riccardo Giacconi, Rayond Davis Jr. (US), Masatoshi Koshiba (Jap)

2003 - Alexei A. Abrikov,(US-Rus), Vitaly I. Ginzburg (Rus). Anthony J. Leggett, (UK-US)

2004 - David J. Gross, H. David Politzer, Frank Wilczek (US)

2005 - Roy glauber, John Hall (both US), and Theodor Haensch (Germany)

2006

2007

2008

IIT JEE 2010 Syllabus for Physics

2009-04-19T02:54:00.000-07:00

IIT JEE 2010 syllabus will be available only when the JEE advertisment is released. You have to prepared using JEE 2009 syllabus up to that time.

Memory Maps for IIT JEE Physics - Mental Map

2009-04-13T09:57:00.000-07:00

Memory is map linking one concept to another concept. Mind map or mental map helps in your memorizing things.

Let me try to identify main concepts in each chapter and link them to more concepts related to each of them

Chapters from "Concepts of Physics Part I and II" by H C Verma

Chapters

1. Introduction to physics

Physics - Understanding nature - Mathematics - Units - Dimensions

Units - Fundamental quantities - Derived quanties - SI units - SI Prefixes

SI Units - Metre - Kilogram - Second - Ampere - Kelvin - Mole

Dimension - Homogenuity - Conversion of Units

Understanding Nature - Structure of world

Order of magnitude

2. Physics and mathematics

3. Rest and motion :kinematics

Rest - Motion – displacement – Speed – Velocity – Acceleration – Frame of Reference

Displacement – Distance moved

Speed - average speed - instantaneous speed

Velocity - Average velocity - instantaneous velocity – Acceleration

Acceleration - Average acceleration - instantaneous acceleration

Motion - straight line - Motion in a plane - Projectile motion

Frame of Reference – Change in Frame of Reference

4. The forces

Forces - Gravitational forces - Electromagnetic (EM) forces - Nuclear Forces - Weak forces - Scope of Classical physics

Gravitational forces - G (universal constant 6.67 *106-11 N-m^2/kg^2) – Acceleration due to gravity g = GM/R^2) - Spherical body treated as a point mass at their centres

Electromagnetic (EM) forces – Coulomb forces – Forces between two surfaces in contact – Tension in a string or rope – Force due to a spring

Nuclear Forces – Exerted when interacting particles are protons or neutrons

Weak forces – Forces responsible for beta decay – antinutrino - positron

Scope of Classical physics – Applicable to bodies of linear sizes greater than 10^-6 m – Subatomic bodies – Quantum physics applicable – If the velocity of bodies are comparable to 3*10^* m/s relativistic mechanics is applicable.

5. Newtons law of motion

Newtons laws of motion - First law - second law - third law - Pseudo forces - Inertia

Newton's First law – Inertial frame of reference – Earth - Noninertial frame of reference

Newton's second law –( f = ma) - Freebody diagram

Newton's third law of motion – action - reaction

Pseudo forces – inertial forces

Inertia – a property which determines acceleration

6. Friction

Friction – Normal contact force – Friction - Kinetic friction - Static friction - Laws of friction - Atomic level friction – Rolling Friction

Kinetic friction – Opposite to motion – Coefficient of Kinetic friction –

Static friction - Limiting friction – Max. Static friction - Coefficient of static friction

Measurement of friction Coefficients- Horizontal table method – Inclined table method

7. Circular motion

Circular motion - Angular variables - Unit vectors along the radius and the tangent – Acceleration - Banking of roads in circular turns - Centrifugal force – Effects of earth's rotation

Angular variables – Angular position – Angular velocity – Angular acceleration – tangential acceleration

Unit vectors along the radius and the tangent – Tangential Unit vectors - Radial Unit vectors

Acceleration – Uniform circular motion - Nonuniform circular motion

Effects of earth's rotation – Colatitude – apparent weight

8. Work and energy

Work and energy - Work - Kinetic energy - Work energy theorem - Potential energy - Conservative and nonconservative forces - Gravitational potential energy - Different forms of energy - Mass energy equivalence

Work - Calculation of work done -

Potential energy - Potential energy of a compressed or extended spring - Gravitational potential energy

9. Centre of mass,linear momentum,collision

Centre of mass, linear momentum, collision - Centre of mass - Motion of the Centre of mass - Linear momentum – Collision – Impulse

Centre of mass - Centre of mass of continuous bodies - Motion of the Centre of mass

Linear momentum - Its conservation principle - Rocket propulsion

Collision - Elastic collision in one dimension - Perfectly inelastic collision in one dimension - Coefficient of restitution - Elastic collision in two dimensions

Impulse - Impulsive force

10. Rotational mechanics
11. Gravitation
12. Simple harmonic motion
13. Fluid mechanics
14. Some mechanical properties of matter
15. Wave motion and waves on a string
16. Sound waves
17. Light waves
18. Geometrical optics
19. Optical instruments
20. Dispersion and spectra
21. Speed of light
22. Photometry
23. Heat and Temperature
24. Kinetic theory of Gases
25. Calorimetry
26. Laws of Thermodynamics
27. Specific Heat of Capacities of Gases
28. Heat transfer
29. Electric Field and Potential
30. Gauss's Law
31. Capacitors
32. Electric Current in Conductors
32. Thermal and Chemical effects of Electric Current
33. Thermal and Chemical Effects of Electric Current
34. Magentic Field
35. Magnetic field due to a Current
36. Permanent Magnets
37. Magnetic Properties of Matter
38. Electro Magentic Induction
39. Alternating current
40. electromagentic Waves
41. Electric Current through Gases
42. Photoelectric Effect and Waveparticle Duality
43. Bohr's Model and Physics of Atom
44. X-Rays
45. SemiConductors and Semiconductor Devices
46. Nucleus
47. The Special Theory of Relativity

CBSE 2010 Class XI (2008-09) Syllabus

2009-04-12T23:56:00.000-07:00

PHYSICS (Code No. 042)

Senior Secondary stage of school education is a stage of transition from general
education to discipline-based focus on curriculum. The present updated syllabus keeps
in view the rigour and depth of disciplinary approach as well as the comprehension
level of learners. Due care has also been taken that the syllabus is not heavy and is at
the same time, comparable to the international standards. Salient features of the syllabus
include:
_ Emphasis on basic conceptual understanding of the content.
_ Emphasis on use of SI units, symbols, nomenclature of physical quantities and
formulations as per international standards.
_ Providing logical sequencing of units of the subject matter and proper placement of
concepts with their linkage for better learning.
_ Reducing the curriculum load by eliminating overlapping of concepts/ content within
the discipline and other disciplines.
_ Promotion of process-skills, problem-solving abilities and applications of Physics
concepts.

Besides, the syllabus also attempts to
_ strengthen the concepts developed at the secondary stage to provide firm foundation
for further learning in the subject.
_ expose the learners to different processes used in Physics-related industrial and
technological applications.
_ develop process-skills and experimental, observational, manipulative, decision
making and investigatory skills in the learners.
_ promote problem solving abilities and creative thinking in learners.
_ develop conceptual competence in the learners and make them realize and appreciate
the interface of Physics with other disciplines.

COURSE STRUCTURE

Class XI (Theory)
One Paper Three Hours Max Marks: 70
Class XI Weightage
Unit I Physical World & Measurement 03
Unit II Kinematics 10
Unit III Laws of Motion 10
Unit IV Work, Energy & Power 06
Unit V Motion of System of particles & Rigid Body 06
Unit VI Gravitation 05
Unit VII Properties of Bulk Matter 10
Unit VIII Thermodynamics 05
Unit XI Behaviour of Perfect Gas & Kinetic Theory of gases 05
Unit X Oscillations & Waves 10
Total 70

Unit I: Physical World and Measurement (periods 10)

Physics - scope and excitement; nature of physical laws; Physics, technology and society.
Need for measurement: Units of measurement; systems of units; SI units, fundamental
and derived units. Length, mass and time measurements; accuracy and precision of
measuring instruments; errors in measurement; significant figures.
Dimensions of physical quantities, dimensional analysis and its applications.

Unit II: Kinematics (Periods 30)

Frame of reference. Motion in a straight line: Position-time graph, speed and velocity.
Uniform and non-uniform motion, average speed and instantaneous velocity.
Uniformly accelerated motion, velocity-time, position-time graphs, relations for uniformly accelerated motion (graphical treatment).
Elementary concepts of differentiation and integration for describing motion.
Scalar and vector quantities: Position and displacement vectors, general vectors and
notation, equality of vectors, multiplication of vectors by a real number; addition and
subtraction of vectors. Relative velocity.
Unit vector; Resolution of a vector in a plane - rectangular components. Motion in a
plane. Cases of uniform velocity and uniform acceleration-projectile motion. Uniform
circular motion.

Unit III: Laws of Motion (Periods 16)

Intuitive concept of force. Inertia, Newton’s first law of motion; momentum and Newton’s second law of motion; impulse; Newton’s third law of motion. Law of conservation of linear momentum and its applications.
Equilibrium of concurrent forces. Static and kinetic friction, laws of friction, rolling friction.
Dynamics of uniform circular motion: Centripetal force, examples of circular motion
(vehicle on level circular road, vehicle on banked road).

Unit IV: Work, Energy and Power (Periods 16)

Scalar product of vectors. Work done by a constant force and a variable force; kinetic
energy, work-energy theorem, power.
Notion of potential energy, potential energy of a spring, conservative forces: conservation
of mechanical energy (kinetic and potential energies); non-conservative forces: elastic
and inelastic collisions in one and two dimensions.

Unit V: Motion of System of Particles and Rigid Body (Periods 18)

Centre of mass of a two-particle system, momentum conversation and centre of mass
motion. Centre of mass of a rigid body; centre of mass of uniform rod.
Vector product of vectors; moment of a force, torque, angular momentum, conservation
of angular momentum with some examples.
Equilibrium of rigid bodies, rigid body rotation and equations of rotational motion,
comparison of linear and rotational motions; moment of inertia, radius of gyration.
Values of moments of inertia for simple geometrical objects (no derivation). Statement of
parallel and perpendicular axes theorems and their applications.

Unit VI: Gravitation (Periods 14)

Keplar’s laws of planetary motion. The universal law of gravitation.
Acceleration due to gravity and its variation with altitude and depth.
Gravitational potential energy; gravitational potential. Escape velocity. Orbital velocity
of a satellite. Geo-stationary satellites.

Unit VII: Properties of Bulk Matter (Periods 28)

Elastic behaviour, Stress-strain relationship, Hooke’s law, Young’s modulus, bulk modulus, shear, modulus of rigidity.
Pressure due to a fluid column; Pascal’s law and its applications (hydraulic lift and hydraulic brakes). Effect of gravity on fluid pressure.
Viscosity, Stokes’ law, terminal velocity, Reynold’s number, streamline and turbulent
flow. Bernoulli’s theorem and its applications.
Surface energy and surface tension, angle of contact, application of surface tension ideas to drops, bubbles and capillary rise.
Heat, temperature, thermal expansion; specific heat - calorimetry; change of state - latent heat.
Heat transfer-conduction, convection and radiation, thermal conductivity, Newton’s law of cooling.

Unit VIII: Thermodynamics (Periods 12)

Thermal equilibrium and definition of temperature (zeroth law of thermodynamics). Heat, work and internal energy. First law of thermodynamics.
Second law of thermodynamics: reversible and irreversible processes. Heat engines and
refrigerators.

Unit IX: Behaviour of Perfect Gas and Kinetic Theory (Periods 8)

Equation of state of a perfect gas, work done on compressing a gas.
Kinetic theory of gases - assumptions, concept of pressure. Kinetic energy and temperature; rms speed of gas molecules; degrees of freedom, law of equipartition of energy (statement only) and application to specific heats of gases; concept of mean free path, Avogadro’s number.

Unit X: Oscillations and Waves (Periods 28)

Periodic motion - period, frequency, displacement as a function of time. Periodic functions.
Simple harmonic motion (S.H.M) and its equation; phase; oscillations of a spring–restoring force and force constant; energy in S.H.M.-kinetic and potential energies; simple pendulum–derivation of expression for its time period; free, forced and damped oscillations (qualitative ideas only), resonance.
Wave motion. Longitudinal and transverse waves, speed of wave motion. Displacement
relation for a progressive wave. Principle of superposition of waves, reflection of waves,
standing waves in strings and organ pipes, fundamental mode and harmonics, Beats,
Doppler effect.

Practicals
Note: Every student will perform 10 experiments (5 from each section) and 8 activities (4
from each section) during the academic year.
Two demonstration experiments must be performed by the teacher with participation of
students. The students will maintain a record of these demonstration experiments. Schools are advised to see the guidelines for evaluation in practicals for Class XII. Similar pattern may the followed for Class XI.

SECTION A
Experiments
1. Use of Vernier Callipers
(i) to measure diameter of a small spherical/cylindrical body.
(ii) to measure dimensions of a given regular body of known mass and hence find its
density.
(iii) to measure internal diameter and depth of a given beaker/calorimeter and hence
find its volume.
2. Use of screw gauge
(i) to measure diameter of a given wire, (ii) to measure thickness of a given sheet
(iii) to measure volume of an irregular lamina
3. To determine radius of curvature of a given spherical surface by a spherometer.
4. To find the weight of a given body using parallelogram law of vectors.
5. Using a simple pendulum, plot L-T and L-T2 graphs. Hence find the effective length of
second’s pendulum using appropriate graph.
6. To study the relationship between force of limiting friction and normal reaction and to find co-efficient of friction between a block and a horizontal surface.
7. To find the downward force, along an inclined plane, acting on a roller due to gravitational pull of the earth and study its relationship with the angle of inclination by plotting graph between force and sin.

Activities

1. To make a paper scale of given least count, e.g. 0.2cm, 0.5cm.
2. To determine mass of a given body using a metre scale by principle of moments.
3. To plot a graph for a given set of data, with proper choice of scales and error bars.
4. To measure the force of limiting friction for rolling of a roller on a horizontal plane.
5. To study the variation in range of a jet of water with angle of projection.
6. To study the conservation of energy of a ball rolling down on inclined plane (using a
double inclined plane).
7. To study dissipation of energy of a simple pendulum by plotting a graph between square of amplitude and time.

SECTION B

Experiments

1. To determine Young’s modulus of elasticity of the material of a given wire.
2. To find the force constant of a helical spring by plotting graph between load and extension.
3. To study the variation in volume with pressure for a sample of air at constant temperature by plotting graphs between P and V, and between P and I/V.
4. To determine the surface tension of water by capillary rise method.
5. To determine the coefficient of viscosity of a given viscous liquid by measuring terminal velocity of a given spherical body.
6. To study the relationship between the temperature of a hot body and time by plotting a
cooling curve.
7. (i) To study the relation between frequency and length of a given wire under constant
tension using sonometer.
(ii) To study the relation between the length of a given wire and tension for constant
frequency using sonometer.
8. To find the speed of sound in air at room temperature using a resonance tube by two resonance positions.
9. To determine specific heat of a given (i) solid (ii) liquid, by method of mixtures.

Activities

1. To observe change of state and plot a cooling curve for molten wax.
2. To observe and explain the effect of heating on a bi-metallic strip.
3. To note the change in level of liquid in a container on heating and interpret the observations.
4. To study the effect of detergent on surface tension by observing capillary rise.
5. To study the factors affecting the rate of loss of heat of a liquid.
6. To study the effect of load on depression of a suitably clamped metre scale loaded
(i) at its end (ii) in the middle.

Recommended Textbooks.

1. Physics Part-I, Textbook for Class XI, Published by NCERT
2 . Physics Part-II, Textbook for Class XI, Published by NCERT

CBSE Syllabus Physics - Class 12

2009-04-12T23:47:00.000-07:00

Unit I Electrostatics
Unit II Current Electricity
Unit III Magnetic effect of current & Magnetism
Unit IV Electromagnetic Induction and Alternating current
Unit V Electromagnetic Waves
Unit VI Optics
Unit VII Dual Nature of Matter
Unit VIII Atoms and Nuclei
Unit IX Electronic Devices
Unit X Communication Systems

Unit I: Electrostatics (Periods 25)
Electric Charges; Conservation of charge, Coulomb’s law-force between two point charges, forces between multiple charges; superposition principle and continuous charge distribution.
Electric field, electric field due to a point charge, electric field lines; electric dipole, electric field due to a dipole; torque on a dipole in uniform electric field.
Electric flux, statement of Gauss’s theorem and its applications to find field due to infinitely long straight wire, uniformly charged infinite plane sheet and uniformly charged thin spherical shell (field inside and outside).
Electric potential, potential difference, electric potential due to a point charge, a dipole and system of charges; equipotential surfaces, electrical potential energy of a system of two point charges and of electric dipole in an electrostatic field.
Conductors and insulators, free charges and bound charges inside a conductor. Dielectrics and electric polarisation, capacitors and capacitance, combination of capacitors in series and in parallel, capacitance of a parallel plate capacitor with and without dielectric medium between the plates, energy stored in a capacitor. Van de Graaff generator.

Unit II: Current Electricity (Periods 22)
Electric current, flow of electric charges in a metallic conductor, drift velocity, mobility and their relation with electric current; Ohm’s law, electrical resistance, V-I characteristics (linear and non-linear), electrical energy and power, electrical resistivity and conductivity. Carbon resistors, colour code for carbon resistors; series and parallel combinations of resistors; temperature dependence of resistance.
Internal resistance of a cell, potential difference and emf of a cell, combination of cells in series and in parallel.
Kirchhoff’s laws and simple applications. Wheatstone bridge, metre bridge.
Potentiometer - principle and its applications to measure potential difference and for comparing emf of two cells; measurement of internal resistance of a cell.

Unit III: Magnetic Effects of Current and Magnetism (Periods 25)
Concept of magnetic field, Oersted’s experiment.
Biot - Savart law and its application to current carrying circular loop.
Ampere’s law and its applications to infinitely long straight wire, straight and toroidal solenoids.
Force on a moving charge in uniform magnetic and electric fields. Cyclotron.
Force on a current-carrying conductor in a uniform magnetic field. Force between two parallel current-carrying conductors-definition of ampere. Torque experienced by a current loop in uniform magnetic field; moving coil galvanometer-its current sensitivity and conversion to ammeter and voltmeter.

Current loop as a magnetic dipole and its magnetic dipole moment. Magnetic dipole moment of a revolving electron. Magnetic field intensity due to a magnetic dipole (bar magnet) along its axis and perpendicular to its axis. Torque on a magnetic dipole (bar magnet) in a uniform magnetic field; bar magnet as an equivalent solenoid, magnetic field lines; Earth’s magnetic field and magnetic elements.
Para-, dia- and ferro - magnetic substances, with examples. Electromagnets and factors affecting their strengths. Permanent magnets.

Unit IV: Electromagnetic Induction and Alternating Currents (Periods 20)
Electromagnetic induction; Faraday’s law, induced emf and current; Lenz’s Law, Eddy currents.
Self and mutual inductance.
Need for displacement current.
Alternating currents, peak and rms value of alternating current/voltage; reactance and impedance;
LC oscillations (qualitative treatment only), LCR series circuit, resonance; power in AC circuits, wattless current.
AC generator and transformer.

Unit V: Electromagnetic waves (Periods 4)
Displacement current, Electromagnetic waves and their characteristics (qualitative ideas only).
Transverse nature of electromagnetic waves.
Electromagnetic spectrum (radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays) including elementary facts about their uses.

Unit VI: Optics (Periods 30)
Reflection of light, spherical mirrors, mirror formula. Refraction of light, total internal reflection and its applications, optical fibres, refraction at spherical surfaces, lenses, thin lens formula, lensmaker’s formula. Magnification, power of a lens, combination of thin lenses in contact. Refraction and dispersion of light through a prism.
Scattering of light - blue colour of the sky and reddish appearance of the sun at sunrise and sunset.
Optical instruments: Human eye, image formation and accommodation, correction of eye defects (myopia, hypermetropia, presbyopia and astigmatism) using lenses. Microscopes and astronomical telescopes (reflecting and refracting) and their magnifying powers.
Wave optics: wave front and Huygens’ principle, reflection and refraction of plane wave at a plane surface using wave fronts. Proof of laws of reflection and refraction using Huygens’ principle.
Interference, Young’s double slit experiment and expression for fringe width, coherent sources and sustained interference of light. Diffraction due to a single slit, width of central maximum. Resolving power of microscopes and astronomical telescopes. Polarisation, plane polarised light; Brewster’s law, uses of plane polarised light and Polaroids.

Unit VII: Dual Nature of Matter and Radiation (Periods 8)

Dual nature of radiation. Photoelectric effect, Hertz and Lenard’s observations; Einstein’s
photoelectric equation-particle nature of light.
Matter waves-wave nature of particles, de Broglie relation. Davisson-Germer experiment.

Unit VIII: Atoms & Nuclei (Periods 18)

Alpha-particle scattering experiment; Rutherford’s model of atom; Bohr model, energy levels, hydrogen spectrum.
Composition and size of nucleus, atomic masses, isotopes, isobars; isotones. Radioactivityalpha, beta and gamma particles/rays and their properties; radioactive decay law.
Mass-energy relation, mass defect; binding energy per nucleon and its variation with
mass number; nuclear fission, nuclear reactor, nuclear fusion.

Unit IX: Electronic Devices (Periods 18)

Semiconductors; semiconductor diode – I-V characteristics in forward and reverse bias, diode as a rectifier; I-V characteristics of LED, photodiode, solar cell, and Zener diode; Zener diode as a voltage regulator. Junction transistor, transistor action, characteristics of a transistor; transistor as an amplifier (common emitter configuration) and oscillator. Logic gates (OR, AND, NOT, NAND and NOR). Transistor as a switch.

Unit X: Communication Systems (Periods 10)

Elements of a communication system (block diagram only); bandwidth of signals (speech, TV and digital data); bandwidth of transmission medium. Propagation of electromagnetic waves in the atmosphere, sky and space wave propagation. Need for modulation. Production and detection of an amplitude-modulated wave.

Practicals
Every student will perform 10 experiments (5 from each section) & 8 activities (4 from each section) during the academic year. Two demonstration experiments must be performed by the teacher with participation of students. The students will maintain a record of these demonstration experiments.

SECTION A
Experiments
1. To determine resistance per cm of a given wire by plotting a graph of potential difference versus current.
2. To find resistance of a given wire using metre bridge and hence determine the specific
resistance of its material.
3. To verify the laws of combination (series/parallel) of resistances using a metre bridge.
4. To compare the emf of two given primary cells using potentiometer.
5. To determine the internal resistance of given primary cell using potentiometer.
6. To determine resistance of a galvanometer by half-deflection method and to find its figure of merit.
7. To convert the given galvanometer (of known resistance and figure of merit) into an ammeter and voltmeter of desired range and to verify the same.
8. To find the frequency of the a.c. mains with a sonometer.

Activities
1. To measure the resistance and impedance of an inductor with or without iron core.
2. To measure resistance, voltage (AC/DC), current (AC) and check continuity of a given
circuit using multimeter.
3. To assemble a household circuit comprising three bulbs, three (on/off) switches, a fuse
and a power source.
4. To assemble the components of a given electrical circuit.
5. To study the variation in potential drop with length of a wire for a steady current.
6. To draw the diagram of a given open circuit comprising at least a battery, resistor/rheostat, key, ammeter and voltmeter. Mark the components that are not connected in proper order and correct the circuit and also the circuit diagram.

SECTION B

Experiments
1. To find the value of v for different values of u in case of a concave mirror and to find the focal length.
2. To find the focal length of a convex lens by plotting graphs between u and v or between l/u and l/v.
3. To find the focal length of a convex mirror, using a convex lens.
4. To find the focal length of a concave lens, using a convex lens.
5. To determine angle of minimum deviation for a given prism by plotting a graph between angle of incidence and angle of deviation.
6. To determine refractive index of a glass slab using a travelling microscope.
7. To find refractive index of a liquid by using (i) concave mirror, (ii) convex lens and plane mirror.
8. To draw the I-V characteristic curve of a p-n junction in forward bias and reverse bias.
9. To draw the characteristic curve of a zener diode and to determine its reverse break
down voltage.
10. To study the characteristics of a common - emitter npn or pnp transistor and to find
out the values of current and voltage gains.

Activities
1. To study effect of intensity of light (by varying distance of the source) on an L.D.R.
2. To identify a diode, an LED, a transistor, and IC, a resistor and a capacitor from mixed
collection of such items.
3. Use of multimeter to (i) identify base of transistor. (ii) distinguish between npn and pnp type transistors. (iii) see the unidirectional flow of current in case of a diode and an LED.
(iv) check whether a given electronic component (e.g. diode, transistor or I C) is in working order.
4. To observe refraction and lateral deviation of a beam of light incident obliquely on a glass slab.
5. To observe polarization of light using two Polaroids.
6. To observe diffraction of light due to a thin slit.
7. To study the nature and size of the image formed by (i) convex lens (ii) concave mirror, on
a screen by using a candle and a screen (for different distances of the candle from the lens/mirror).
8. To obtain a lens combination with the specified focal length by using two lenses from the given set of lenses.

B. Evaluation Scheme for Practical Examination:
_ One experiment from any one section 8 Marks
_ Two activities (one from each section) (4+4) 8 Marks
_ Practical record (experiments & activities) 6 Marks
_ Record of demonstration experiments & Viva based on these experiments 3 Marks
_ Viva on experiments & activities 5 Marks
Total 30 Marks
Recommended Textbooks.
1. Physics Part-I, Textbook for XII, Published by NCERT
2. Physics Part-II, Textbook for XII, Published by NCERT

Source: http://www.cbse.nic.in/welcome.htm

Study Plan - Study Guide

2009-04-11T22:48:00.000-07:00

I am posting a study plan for each of the chapter. The plan is of 20 days in which first 10 days is for study of the lesson and next 10 days is for revision and solving problems. A candidate must be able to master the chapter in these 20 days by solving every question and problem in the HC Verma text book. By taking a target of 3 chapters in each month for the detailed study 10 days each chapter, candidates can complete each text or one year's portion during the period May to December.

Click on the label HC Verma Study Guide for the plan of various chapters. I completed posting for many chapters of Book 1 and plan to complete for the required number of chapters by May 1.

Blog status

2009-03-07T22:22:00.000-08:00

I started revising the study guides of each chapter by providing a 20 days schedule for the first time study and revision of the chapter. I posted the schedule for the first chapter today. I plan to do similar posting for all the chapters.

COMPTON EFFECT

2009-02-10T07:36:00.000-08:00

Arthur Compton and Debye both provided in 1922 a very simple mathematical framework for the momentum of these photons with Compton having experimental evidence from firing X-Rays of known frequency into graphite and looking at recoil electrons.

Let E = mc² = hf for a photon, where f is frequency, and "m" is the mass "equivalent" of the photon given they have no "rest mass". (It is important to recognise that stopping a photon to measure its mass eliminates it -so it has no "at rest" mass - crucial in Special Relativity where, to travel at the speed of light, mass would otherwise become infinite.)

Having "rigged" this mass problem,

p = momentum = mc (mass x velocity) = hf/c = E/c = h/l

The experiment shows that X-Rays and electrons behave exactly like ball bearings colliding on a table top using the same 2D vector diagrams. They enter the graphite at one wavelength and leave at a longer wavelength as they have transfered both momentum and kinetic energy to an electron. Momentum and energy are conserved in the collision if we accept the equation above for momentum of light.

When the photon enters at l0 and leaves at l1, its energy has changed from E0 to E1 and momentum from E0/c to E1/c with a change in direction of q. The electron gains Ek = E0 - E1

See for a diagram and more details

http://www.launc.tased.edu.au/online/sciences/physics/compton.html

The Compton Effect ( a different explanation)

Convincing evidence that light is made up of particles (photons), and that photons have momentum, can be seen when a photon with energy hf collides with a stationary electron. Some of the energy and momentum is transferred to the electron (this is known as the Compton effect), but both energy and momentum are conserved in this elastic collision. After the collision the photon has energy hf' and the electron has acquired a kinetic energy K.

Conservation of energy: hf = hf' + K

Combining this with the momentum conservation equations, it can be shown that the wavelength of the outgoing photon is related to the wavelength of the incident photon by the equation:

Δλ = λ' - λ = (h/m_ec)(1 - cosq)

The combination of factors h/m_ec = 2.43 x 10^-12 m, where m_e is the mass of the electron, is known as the Compton wavelength. The collision causes the photon wavelength to increase by somewhere between 0 (for a scattering angle of 0°) and twice the Compton wavelength (for a scattering angle of 180°).

Source:
http://physics.bu.edu/~duffy/semester2/c35_compton.html

It has problems and examples and demonstration also.

Schrodinger’s Equation

2009-02-07T08:27:00.000-08:00

Quantum mechanics describes the spectra in a much better way than Bohr’s model.

Electron has a wave character as well as a particle character. The wave function of the electron ψ(r,t ) is obtained by solving Schrodinger’s wave equation. The probability of finding an electron is high where | ψ(r,t )|² is greater. Not only the information about the electron’s position but information about all the properties including energy etc. that we calculated using the Bohr’s postulates are contained in the wave function of ψ(r,t).

Quantum Mechanics of the Hydrogen Atom

The wave function of the electron ψ(r,t) is obtained from the Schrodinger’s equation

-(h²/8π²m) [∂²ψ /∂x² + ∂²ψ /∂y² + ∂²ψ/∂z²] - Ze²ψ/4πε₀r = E ψ

where
(x.y,z ) refers to a point with the nucleus as the origin and r is the distance of this point from the nucleus.
E refers to the energy.
Z is the number of protons.

There are infinite number of functions ψ(r,t) which satisfy the equations.

These functions may be characterized by three parameters n,l, and m_l.

For each combination of n,l, and m_l there is an associated unique value of E of the atom of the ion.

The energy of the wave function of characterized by n,l, and m_l depends only on n and may be written as

En = - mZ²e⁴/8 ε₀²h²n²

These energies are identical with Bohr’s model energies.

The paramer n is called the principal quantum number, l the orbital angular momentum quantum number and m_l. The magnetic quantum number.

When n = 1, the wave function of the hydrogen atom is

ψ(r) = ψ₁₀₀ = √(Z³/ π a₀²) *(e^{-r/ a₀})

ψ₁₀₀ denotes that n =1, l = 0 and m_l = 0

a₀ = Bohr radius

In quantum mechanics, the idea of orbit is invalid. At any instant the wve function is spread over large distances in space, and wherever ψ≠ 0, the presence of electron may be felt.

The probability of finding the electron in a small volume dV is | ψ(r)| ² dV
We can calculate the probability p(r)dr of finding the electron at a distance between r and r+dr from the nucleus.

In the ground state for hydrogen atom it comes out to be

P(r) = (4/ a₀)r²e ^{-2r/ a₀}

The plot of P(r) versus r shows that P(r) is maximum at r = a₀ Which the Bohr’s radius.

But when we put n =2, the maximum probability comes at two radii one near r = a₀ and the other at r = 5.4 a₀. According to Bohr model all electrons should be at r = 4 a₀.

Ask questions and answer questions about IIT JEE Subjects

2009-01-01T01:49:00.000-08:00

KNOWLEDGE QUESTION AND ANSWER BOARD
http://knol.google.com/k/narayana-rao-kvss/-/2utb2lsm2k7a/654#

Transmutation of elements

2008-12-07T03:05:00.000-08:00

Question

Was it found by Rutherford and Chadwick that oxygen and carbon cannot be transmuted by bombarding them with alpha particles???

I searched internet and got this one.

Russell was able to demonstrate the transmutation of gases in the Bloomfield, New Jersey research laboratory at the Westinghouse Lamp Company on Sept. 30, 1927. Transmutation of hydrogen and oxygen to nitro- gen, and, nitrogen to oxygen and hydrogen was accomplished.
See reference
http://padrak.com/ine/NEN_4_11_3.html

Early Atomic Models

2008-11-10T10:00:00.001-08:00

The idea that all matter is made of very small indivisible particles is very old.

Robert Boyle’s study of compression and expansion of air brings out the idea that air is made of tiny particles with lot of empty space between the particles.

The smallest unit of an element which carries all the properties of the element is called an atom.

Experiments on discharge tube, measurement of e/m by Thomson etc. established the existence of negatively charged electrons in the atoms.

Because atoms are electrically neutral, a search for the positive charge inside the atom was started.

Thomson’s Model of the atom

2008-11-10T09:59:00.000-08:00

Thomson (1898) suggested that the atom is a positively charged solid sphere in which electrons are embedded in sufficient number to create a neutral atom. This model of the atom could explain why only negatively charged particles are being emitted when a metal is heated. This model was also useful to explain the formation of ions and ionic compounds.

Lenard's Suggestion on Atomic Structure

2008-11-10T09:58:00.000-08:00

Lenard observed that cathode rays are passing through thin material without any deviation. According to him, this was so because, there is a lot of empty space in atoms. Hence the positive charged particles are also tiny like electrons.

Hydrogen Spectra

2008-11-10T09:57:00.000-08:00

If hydrogen gas is enclosed in a sealed tube and heat to high temperatures, it emits radiation. If this radiation is passed through a prsim, components are different wavelengths get deviated by different amounts and we get the hydrogen spectra on a screen. In the spectra of hydrogen atom, it is observed that light of wavelength 656.3 nm and then light of wave length 486.1 nm are present. Hydrogen atoms do not emit any radiation between 656.3 nm and 486.1 nm. Similarly radiation is observed at 434.1 nm and 4202.nm.

In the invisible region also, there is radiation emitted by the hydrogen atom at discrete wavelengths.

The wavelengths nicely fit the equation

1/λ = R [1/n² - 1/m²]

where R = 1.09737*10^7 m^-1.
n and m are integers with m>n.

The spectrum in the ultraviolet region is called Lyman series and you get the series by setting n = 1.

The hydrogen spectrum in the visible region is called Balmer series and you get the series by setting n = 2.

The hydrogen spectrum in infrared region is called Paschen series and you get the series by setting n= 3.

Rutherford's Model

2008-11-10T09:56:00.002-08:00

Rutherford experimented with alpha rays or particles. When he bombarded gold foils with alpha particles, Many went without deviation, some had some deviation and some were deflected by more than 90 and came back. Hence he made a conclusion that there was a particle with a mass equivalent to alpha particle inside the atom. The mass of an atom is concentrated in this particle.

The size of this particle was also estimated by Rutherford. Its linear size is 10 fermi ( 1 fermi is equal to 1 femtometre = 10^-15 m).

Rutherford proposed that the atom contains a positively charged tiny particle called nucleus. It contains the entire mass of the atom. Outside this nucleus, at some distance, electrons move around. The positive of charge of nucleus is exactly equal to the negative charge of the electrons of the atom.

Because electrons are very very light compared to the nucleus, due to heat only electrons come out.

Movement of electrons is to brought in and the coulomb force between the nucleus and the electron is assumed to provide only centripetal force to make the electron rotate in a circular motion.

Difficulties with Rutherford’s Model

2008-11-10T09:56:00.001-08:00

Rutherford’s model assumes that the electron rotates around the nucleus. Maxwell’s equations of a electromagnetism show that accelerated electron must continuously emit electromagnetic radiation. But a hydrogen does not emit radiation at ground level energy or normal energy. It emits radiation only when heated. Also, if it emits radiation it will lose energy and the radius of its circular motion will decreases and finally it will fall into the nucleus. Hence, the atomic model proposed by Rutherford needs modification. Bohr proposed such modifications.

Bohr's Postulates and Model

2008-11-10T09:55:00.000-08:00

1. The electrons revolve around the nucleus in circular orbits.
2. the orbit of the electron around the nucleus can be only some special values of radius. In these special radii orbits, the electron does not radiate energy as expected from Maxwell’s laws. These orbits are called stationary orbits.
3. The energy of the atom has a definite value when electrons are in a given stationary orbit. But the if more energy is provided to the atom, the electron can jump from one stationary orbit to another stationary orbit of higher energy. If it jumps from an orbit of higher energy (E2) to an orbit of lower energy (E1), it emits a photon of radiation. The energy of the emitted photon will be E2 – E1.

The wave length of the emitted radiation is given by the Einstein-Planck equation

E2-E1 = hυ = hc/λ

4. In stationary orbits, the angular momentum l of the electron about the nucleus is an in integral multiple of the Planck constant h divided by 2 π.

l = nh/2 π

This assumption is called Bohr’s quantization rule.

Energy of an Hydrogen Atom

2008-11-10T09:53:00.000-08:00

Assume that the nucleus has a positive charge Ze ( there are z protons each with positive charge e).

By equating the coulomb force acting between Ze and e to the centripetal acceleration mv²/r, we get r the radius at which the electron revolves.

r = Ze²/4π ε₀v²

From Bohr’s quantization rule,

mvr = nh/2 π
where n is a positive integer

Eliminating v from both the equations we get

r = ε₀h²n²/πmZe²

We get expression for v as

v = Ze²/2 ε₀hn

Hence allowed radii are proportinal to n² and for each value of n = 1,2,3…we allowed orbits.

The smallest radius orbit will have n = 1.

As we have expression for v, we can give an expression for kinetic energy when electron is in nth orbit is

K = ½ mv² = mZ²e⁴/8 ε₀²h²n²

The potential energy of the atom is

V = - Ze²/4π ε₀r = -mZ²e⁴/4ε₀²h²n²

The expression for potential energy is obtained by assuming the potential energy to be zero when the nucleus and the electron are widely separated.

The total energy of the atom is

E = K+V = - mZ²e⁴/8 ε₀²h²n²

When an atom is n^th stationary orbit, it is said to be in the n^th energy state.

In giving an expression for the total energy of the atom, kinetic energy of the electron and potential energy of the electron-nucleus pair are considered. Kinetic energy of the nucleus is assumed to be negligible.

Bohr’s postulates can be used to find the allowed energies of the hydrogen atom when its single electron is in various stationary orbits. The methodology can be used any hydrogen like ions which have only one electron.. Therefore it is valid for He⁺, Li⁺⁺, Be⁺⁺⁺ etc.

Radii of Different Orbit of Hydrogen Like Ion

2008-11-10T09:50:00.000-08:00

r the radius at which the electron revolves.

r = Ze²/4π ε₀v²

For hydrogen, z =1 and we get r1 as 53 picometre ( 1pm = 10^-12 m) or 0.053 nm. This length is called the Bohr radius and is a convenient unit for measuring lengths in atomic physics. It is denoted by me as the symbol a₀ (In HC Verma a different symbol is given. I am using this symbol as a convenience).

In terms of Bohr radius the second allowed radius is 4 a₀ and third is 9 a₀ and so on. In general nth orbit of hydrogen atom is n²a₀.

Hydrogen Ion - Ground and Excited States

2008-11-10T09:49:00.000-08:00

The state of an atom with the lowest energy is called its ground state.

The states with higher energies are called excited states.
Energy of hydrogen atom in the ground state is -13.6 eV.
Energy of hydrogen atom in the next excited state, that is n = 2 state is -3.4 eV.

Hydrogen Spectra

2008-11-10T09:48:00.001-08:00

When heated some atoms in the hydrogen become excited and when electrons jump from higher energy levels to lower energy levels in those excited atoms, photons with specific wavelengths are emitted or radiated.

If an electron jumps from mth orbit to nth orbit (m>n), the energy of the atom gets reduced from Em to En. The wavelength of the emitted radiation will be

1/ λ = (Em – En)/hc = RZ²{1/n² - 1/m²]

where R is the Rydberg constant.
R = 1.0973*10^7 m^-

In terms of the Rydberg constant total energy of the atom in the nth state is E = -RhcZ²/n²

For hydrogen atom, when n =1, E = -Rhc and we know its value is -13.6 eV.
Energy of 1 rydberg means -13.6 eV.
Rhc = 13.6eV

Hydrogen Spectra - Series Structure

2008-11-10T09:46:00.002-08:00

Lyman series:
All transitions to n =1 state from higher state give the radiation in Lyman series.

Jumping of the electron from n =2 to n =1 gives
1/ λ = R[1 – 1/2²] = R(1 – ¼) which will give λ = 121.6 nm.

Jumping of the electron from n = ∞ to n = 1 gives

1/ λ = R[1 – 1/∞²] = R(1 -0) which gives λ = 91.2 nm.

Balmer seires
All transitions to n = 2 from higher states given radiations within the range of 656.3 nm and 365.0 nm. These wavelengths fall in the visible region.

Paschen series
The transitions or jumps to n = 3 from higher energy levels give Paschen series in the range 1875 nm to 822 nm.

Ionization Potential

2008-11-10T09:46:00.001-08:00

The energy of the hydrogen atom in ground state is -13.6 eV. If we supply more than 13.6 eV to the hydrogen atom, the electron and the nucleus get separated and electron moves with some kinetic energy independently (Remember plasma in nuclear fusion).
The minimum energy needed to ionize an atom is called ionization energy. The potential difference through which an electron should be accelerated to acquire this much energy is called ionization potential.

Thus ionization energy of hydrogen atom in ground state is 13.6 eV and ionization potential is 13.6 V.

Binding Energy

2008-11-10T09:45:00.000-08:00

Binding energy of a system is defined as the energy released when its constituents are brought from infinity to form the system. Now we know that binding energy of a hydrogen atom is 13.6 eV. The energy is zero when the electron and nucleus at infinite distance. When the electron is brought into n = 1 orbit, the energy becomes -13.6 eV and hence 13.6 eV is released which is the binding energy.

Excitation potential

2008-11-10T09:44:00.000-08:00

The energy needed to take the atom form its ground state to an excited state is called the excitation energy of that excited state.

As the hydrogen atom’s ground state energy is -13.6 eV and its energy when electron is in n =2 orbit is -3.4 eV, we have to supply 10.2 eV to excite a hydrogen atom to its first excited state which is electron in n = 2 orbit.

The potential through which an electron should be accelerated to acquire the excitation energy is the excitation potential.

The excitation potential needed bring hydrogen to its first excited state is 10.2 V.

Limitations of Bohr Model

2008-11-10T09:43:00.002-08:00

Maxwell’s theory of electromagnetism is not replaced or refuted in Bohr's model but it is arbitrarily assumed that in certain orbits, electrons get the licence to disobey the laws of electromagnetism and are allowed not to radiate energy.

Quantum Mechanics of the Hydrogen Atom

2008-11-10T09:37:00.000-08:00

Electron has a wave character as well as a particle character. The wave function of the electron ψ(r,t ) is obtained by solving Schrodinger’s wave equation. The probability of finding an electron is high where | ψ(r,t )|² is greater. Not only the information about the electron’s position but information about all the properties including energy etc. that we calculated using the Bohr’s postulates are contained in the wave function of ψ(r,t).

Quantum Mechanics of the Hydrogen Atom

The wave function of the electron ψ(r,t) is obtained from the Schrodinger’s equation

-(h²/8π²m) [∂²ψ /∂x² + ∂²ψ /∂y² + ∂²ψ/∂z²] - Ze²ψ/4πε₀r = E ψ

where
(x.y,z ) refers to a point with the nucleus as the origin and r is the distance of this point from the nucleus.
E refers to the energy.
Z is the number of protons.

There are infinite number of functions ψ(r,t) which satisfy the equations.

These functions may be characterized by three parameters n,l, and m_l.

For each combination of n,l, and m_l there is an associated unique value of E of the atom of the ion.

The energy of the wave function of characterized by n,l, and m_l depends only on n and may be written as

En = - mZ²e⁴/8 ε₀²h²n²

Production of X-rays

2008-11-09T08:09:00.001-08:00

When highly energetic electrons are made to strike a metal target, electromagnetic radiation comes out. A large part of this radiation has wavelength of the order 0.1 nm (appx 1 A) and is known as X-ray.

Continuous and Characteristic X-rays

2008-11-09T08:08:00.001-08:00

If the X-rasy coming from a coolidge tube are examined for wavelengths present, and the intensity of different wavelengths are measurea and plotted, we can observe that there is a minimum wavelength below which no X-ray is emitted.

The wavelength below which no X-rays are emitted is called the cut-off wavelength or the threshold wavelength.

From the plot it can also be observed that at certain sharply defined wavelengths, the intensity of X-rays is very large. These X-rays are called characteristic X-rays.

At other wavelengths the intensity varies gradually and these X-rays are called continuous X-rays.

K X-Rays

X-rays emitted due to electronic transition from a higher energy state to a vacancy created in the K shell are called K X-rays.

Soft and Hard X-rays

2008-11-09T08:07:00.002-08:00

The X-rays of low wave length are called hard X rays and X rays of large wave length are called soft X rays.

In terms of energy, harder means more energy in is each photon.

Moseley's law

2008-11-09T08:07:00.001-08:00

Square root of frequency of X rays = a(Z-b)

√(v) = a(Z-b)

where Z = position number of element.
a and b are constants

Bragg’s law

2008-11-09T08:06:00.000-08:00

2d sin θ = n λ

d = interplanar spacing of the crystal on which X-rays are incident
θ = is the incident angle at which X-rays are strongly reflected.
n = 1,2,3 …
λ = wave length of X-rays

Application of Bragg’s law:By using a monochromatic X-ray beam (having a single wave length) and noting the angles of strong reflection, the interplanar spacing d and several information about the structure of the solid can be obtained.

Properties of X rays

2008-11-09T08:05:00.002-08:00

X rays are electromagnetic waves of short wave lengths.
So they have many properties common with light.

1. They travel in straight lines in vacuum at a speed equal to that of light.
2. They are diffracted by crystals according to Bragg's law.
3. x-rays do not contain charged particles. hence they are not deflected by electric or magnetic field.
4. They effect a photographic plate. The effect is stronger than light.

Properties which are different than light

1. When incident on certain materials barium platinocyanide, X rays cause fluorescence.
2. When passed through a gas, X rays ionize the molecules of the gas.

Atomic nucleus

2008-11-07T08:54:00.001-08:00

Properties of Nucleus

A nucleus is made of protons and neutrons.

Studies have shown that average nucleus R of a nucleus may be written as

R = R0A^(1/3) .. (46.1)

where R0 = 1.1*10^-15 m ≈ 1.1 fm and A is the mass number

Density within a nucleus is independent of A.

Nuclear Forces

2008-11-07T08:53:00.000-08:00

When nucleons are kept at a separation of the order of femtometre (10^-15 m), a new kind of force, called nuclear force starts acting.

Binding Energy

2008-11-07T08:52:00.000-08:00

If the constituents of a hydrogen atom (a proton and an electron) are brought from infinity to form the atom, 13.6 3V of energy is released. Thus, the binding energy of a hydrogen atom in ground state is 13.6 eV. Also 13.6 eV energy must be supplied to the hydrogen atom in ground state to separate the constituents to large distances.

Similarly, the nucleons are bound together in a nucleus and energy must be supplied to the nucleus to separate the constituent nucleons to large distances. The amount of energy needed to do this is called the binding energy of the nucleus. If nucleons are brought together to form the nucleus from large separation this much energy is released.

It is evident from the above discussion that the rest mass energy of a nucleus is smaller than the rest mass energy of its constituents.

Radioactive decay

2008-11-07T08:46:00.000-08:00

Two main processes by which an unstable nucleus decays are alpha decay and beta decay.

Alpha decay

In alpha decay, the unstable nucleus emits an alpha particle reducing its proton number Z as well as its neutron number N by 2. As the proton number is changed, the element itself is changed and hence the chemical symbol of the residual nucleus is different from that of the original nucleus (Parent nucleus is original nucleus and the resulting nucleus due to decay is called daughter nucleus).

Alpha decay occurs in all nuclei with mass number A>210.

Beta Decay

Beta decay is a process in which either a neutron is converted into a proton or a proton is converted into a neutron.
When a neutron is converted into a proton, an electron and a new particle named antineutrino are created and emitted from the nucleus. The electron emitted from the nucleus is called a beta particle and is denoted by the symbol β-.

If the unstable nucleus has excess protons than needed for stability, a proton converts itself into a neutron. In the process, a positron and a neutrino are created and emitted from the nucleus.

Positron is represented by e+. The neutrino is represented by ν.

When a positron and electron collide, both the particles are destroyed and energy is made available.

The decay which gives beta rays consisting of positrons is called beta plus decay

Electron capture

A nucleus captures one of the atomic electrons, most likely an electron from the K shell, and a proton in the nucleus combines with the electron and converts itself into a neutron. A neutrino is created in process and emitted from the nucleus. So a combination of proton and electron results in neutron and neutrino.

Gamma Decay

When a daughter nucleus is formed due to alpha or beta decay, the nucleus may be at higher energy level compared to its ground or normal state. The electromagnetic radiation emitted in nuclear transitions from higher energy or excited state to ground state is called gamma ray.

Law of Radioactive decay;

2008-11-07T08:45:00.000-08:00

N = N0e- λ t

where
N = number of active nuclei at time t

N0 = number of active nuclei at t = 0.

λ = decay constant

-dN/dt = λN

-dN/dt gives the number of decays per unit time and is called the activity (A) of the sample

A = λN

A = A0e- λ t

Decay constant;

2008-11-07T08:44:00.000-08:00

Law of radioactive decay

N = N0e- λ t

where
N = number of active nuclei at time t

N0 = number of active nuclei at t = 0.

λ = decay constant

Half-life and Mean life;

2008-11-07T08:43:00.000-08:00

Half life:

The time elapased before half the active nuclei decay is called half-life and is denoted by t1/2.

t1/2. = 0.693/ λ

where
λ = decay constant.

Average life of the nuclei of a material

tav. = t1/2/0.693

Properties and Uses of Nuclear Radiation

2008-11-07T08:42:00.000-08:00

Properties and Uses of Nuclear Radiation

Alpha Ray
1. Each particle contains two protons and two neutrons. It is a helium nucleus.
2. It is made of positive particles and hence deflected by electric field as well as magnetic field.
3. Its penetrating power is low. Few cm in air also.
4. They travel at large speeds of the order of 10^6 m/s.
5. All particles from a source and decay scheme have the same energy.
6. Alpha rays produce scintillation (flashes of light) when they strike certain fluorescent materials such as barium platinocynide.
7. It causes ionization in gases.

Beta ray

1. It is a stream of electrons. Electrons are created during nuclear transformation.
2. They are negative particles and hence deflected by electric as well as magnetic fields.
3. Penetrating power greater than alpha rays. They can travel several meters in air before its intensity drops down to small values.
4. Ionizing power is less than alpha rays.
5. beta rays also produced scintillation but it is weak.
6. The energy of particles is not uniform as they share energy with antineutrinos. Energy of beta particles varies from zero to a maximum

Beta plus ray

It has all the properties of beta rays or beta negative rays, except that it is made of positively charged particles.

Gamma Ray

1. Gamma ray is an electromagnetic radiation of short wavelength. Its wavelength is shorted than X-rays.
2. Many properties are similar to X-rays.
3. As there is no charge no deflection in electric or magnetic fields.
4. All the photons coming from a particular gamma decay scheme has the same energy.
5. As it is electromagnetic wave, gamma ray travels with the velocity ‘c’ in vacuum.

Binding energy and its calculation

2008-11-07T08:41:00.000-08:00

Energy from the Nucleus

Nuclear energy may be obtained either by breaking a heavy nucleus into two nuclei of middle weight (fission) or by combining two light nuclei to form a middle weight nucleus (fusion).

Reason: The middle weight nuclei are more tightly bound than heavy weight nuclei. When the nucleons of a heavy nucleus regroup in two middle weight nuclei called fragments the total binding energy increases and the rest mass energy decreases. The difference in energy appears as the kinetic energy of the fragments or in some other form.

In the case of fusion, the light weight nuclei are less tightly bound than the middle weight nuclei. Therefore, if two light weight nuclei combine, the binding energy increases and the rest mass decreases. Energy is released in the form of kinetic energy or in some other external form.

Nuclear Fission

2008-11-07T08:40:00.000-08:00

The rest mass energy of the heavy nucleus represented by E1 is greater than the rest mass energy of the fragments represented by E3. But the energy level of the heavy nucleus is to be increased to E2 to get the fission process started according to classical physics.

But according to quantum mechanics, fission can take place even if no external energy is given. Such a fission process is termed as barrier penetration. The amount of energy created and the time for which it is created through a barrier penetration process are related through Heisenberg uncertainty relation.

∆E. ∆t ≈ h/2 π

Where h is the Planck constant

Barrier penetration is possible but is not easy.

Uranium Fission Reactor

2008-11-07T08:39:00.000-08:00

Breeder Reactors

92238U can capture neutrons and become
92239U. On B radiation it becomes
93239Np. On beta radiation it becomes
94239Pu.

94239Pu when hit by neutron becomes 94240Pu, which is a fissionable material. Thus if out of the 2.47 neutrons produced on average in fission reaction, one neutron is absorbed by 238U we produce fuel equivalent to what is consumed. Such a reactor is called breeder reactor.

Nuclear Fusion

2008-11-07T08:38:00.000-08:00

For he light nuclei to come together with in a distance of 1 fm (femtometer), we need a temperature of the order of 10^9 K. At that temperature electrons are completely detached from atoms and only nuclei remain. It is called plasma. In Sun, the temperature is 1.5*10^7 K and fusion is taking place. So fusion can take place due to barrier penetration process at 10^7 K.

Fusion in Laboratory

2008-11-07T08:26:00.000-08:00

The major problem on earth for fusion reaction is holding plasma at high temperature for extended period of time.

Lawson criterion for fusion reactor

In order to get an energy output greater than the energy input, a fusion reactor should achieve

n τ >10^14 s/cm³

where
n = the density of the interacting particles

τ = confinement time

The quantity n τ in s/cm³ is called Lawson number

Tokamak Design

In this design, the deuterium plasma is contained in a toroidal region by specially designed magnetic field. The directions and magnitudes of the magnetic field are so managed in the toroidal space that whenever a charge plasma particle attempts to go out qv×B force tends to push it back into the toroidal volume.

With such designs, confinement of the plasma has been achieved for short duration of few microseconds.

A large fusion machine known as Joint European Torus (JET) is designed to achieve fusion energy on this principle.

At the Institute of Plasma Research (IPR) Ahmedabad, a small machine named Aditya is functioning on the Tokamak design. This machine is being used to study properties of plasma.

Inertial Confinement

It is an alternate method of confinement of plasma. A small solid pellet is made that contains deuterium and tritium. Intense laser beams are directed on the pellet from many directions on all the sides. The laser vaporizes the pellet converting it into plasma and then compresses it. The density increases by 10^3 to 10^4 time the initial density and temperature raises to high values. Fusion occurs in these conditions. In this method also so far, confinement for very small duration is only achieved.

The source of fuel for fusion is water only and water is abundant in oceans. Also these reactions do not result in radioactive emissions like that of fission.

46. Nucleus - Revision Facilitator

2008-11-07T08:24:00.003-08:00

Recollect points under the topic

If required right click on the topic if link is provided, read the material, close it and come back.

46.1 Atomic nucleus;

46.2 Nuclear Forces

46.3 Binding Energy

46.4 Radioactive decay

46.5 Law of Radioactive decay;

Decay constant

Half-life and Mean life

46.6 Properties and Uses of Nuclear Radiation

46.7 Energy from the Nucleus

46.8 Nuclear Fission

46.9 Uranium Fission Reactor

46.10 Nuclear Fusion

46.11 Fusion in Laboratory

http://iit-jee-physics.blogspot.com/2008/03/concept-review-ch46-nucleus.html

1. Introduction to Physics - Revision Facilitator

2008-11-07T08:21:00.002-08:00

Sections

1. Introduction to physics

1.1 What is Physics
1.2 Physics and Mathematics
1.3 Units
1.4 Definitions of base units
1.5 Dimension
1.6 Uses of dimension
1.7 Order of magnitude
1.8 The structure of world

2. Physics and Mathematics - Revision Facilitator

2008-11-07T08:21:00.001-08:00

2. Physics and mathematics

Sections

2.1 Vectors and scalars
2.2 Equality of vectors
2.3 Addition of vectors
2.4 Multiplication of a vector by a number
2.5 Subtraction of vectors
2.6 Resolution of vectors
2.7 DCT product or scalar product of two vectors
2.8 Cross product or vector product of two vectors
2.9 Differential calculus: dy/dx as rate measure
2.10 Maxima and Minima
2.11 Integral calculus
2.12 Significant digits
2.13 Significant digits in calculations
2.14 Errors in measurements

3. Rest and Motion: Kinematics - Revision Facilitator

2008-11-07T08:20:00.004-08:00

3. Rest and Motion: Kinematics

Sections

3.1 Rest and Motion
3.2 Distance and displacement
3.3 average speed and instantaneous speed
3.4 Average velocity and instantaneous velocity
3.5 Average acceleration and instantaneous acceleration
3.6 Motion in a straight line
3.7 Motion in a plane
3.8 Projectile motion
3.9 Change of frame

Mind Map

Rest - Motion – displacement – Speed – Velocity – Acceleration – Frame of Reference

Displacement – Distance moved

Speed - average speed - instantaneous speed

Velocity - Average velocity - instantaneous velocity – Acceleration

Acceleration - Average acceleration - instantaneous acceleration

Motion - straight line - Motion in a plane - Projectile motion

Frame of Reference – Change in Frame of Reference

4. The forces - Revision Facilitator

2008-11-07T08:20:00.003-08:00

4. The forces

Sections

4.1 Introduction
4.2 Gravitational forces
4.3 Electromagnetic (EM) forces
4.4 Nuclear Forces
4.5 Weak forces
4.6 Scope of Classical physics

Mind Map

Forces - Gravitational forces - Electromagnetic (EM) forces - Nuclear Forces - Weak forces - Scope of Classical physics

Gravitational forces - G (universal constant 6.67 *106-11 N-m^2/kg^2) – Acceleration due to gravity g = GM/R^2) - Spherical body treated as a point mass at their centres

Electromagnetic (EM) forces – Coulomb forces – Forces between two surfaces in contact – Tension in a string or rope – Force due to a spring

Nuclear Forces – Exerted when interacting particles are protons or neutrons

Weak forces – Forces responsible for beta decay – antinutrino - positron

Scope of Classical physics – Applicable to bodies of linear sizes greater than 10^-6 m – Subatomic bodies – Quantum physics applicable – If the velocity of bodies are comparable to 3*10^* m/s relativistic mechanics is applicable.

26. Laws of Thermodynamics - Revision Facilitator

2008-11-07T03:39:00.000-08:00

Recollect some points for each topic.
If you want to read about the topic, right click on the link to open it in a new window, read it, close it and come back here(If a link is there).

26.1 The first law of thermodynamics
26.2 Work done by a gas
26.3 Heat engines
26.4 The second law of thermodynamics
26.5 Reversible and irrerversible processes
26.6 entropy
27.7 Carnot engine

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29. Electric Field and Potential - Revision Facilitator

2008-11-07T00:56:00.000-08:00

Recollect some points for each topic.
If you want to read about the topic, right click on the link to open it in a new window, read it, close it and come back here(If a link is there).

29.1 What is electric charge?
29.2 Coulomb's law
29.3 electric field
29.4 Lines of electric force
29.5 Electric potential energy
29.6 Electric potential
29.7 Electric potential due to a point charge
29.8 Relation between electric field and potential
29.9 Electric dipole
29.10 Torque on an electric dipole placed in an lectric field
29.11 Potential energy of a diple placed in a uniform electric field
29.12 Conductors, insulators nad semiconductors
29.13 The electric field inside a conductor

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Full chaper concept review

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30. Gauss's Law - Revision Facilitator

2008-11-07T00:48:00.000-08:00

Recollect some points for each topic.
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30.1 Flux of electric field through a surface
30.2 Solid angle
30.3 Gauss’s law and its derivation from Couloms’s law
30.4 Gauss's law's application
30.5.Spherical charge distributions
30.6 Earthing a conductor

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Concept review of the full chapter

http://iit-jee-physics.blogspot.com/2008/03/concept-review-ch30-gausss-law.html

31. Capacitors - Revision Facilitator

2008-11-06T02:45:00.000-08:00

Recollect some points for each topic and right click on the link to open it in a new window, read it, close it and come back here.

31.1 Capacitance;
31.2 Calculation of capacitance
31.3 Capacitors in series and parallel;
31.4 Parallel plate capacitor
31.5 Energy stored in a capacitor.
31.6 Dielectrics
31.7 Parallel plate capacitor with dielectrics;
31.8 An alternative form of Gauss's law
31.9 Electric field due to a point charge q placed in a an infinite dielectric
31.10 Energy in the Electric field in a dielectric
31.11 Corona discharge
31.12 High voltage generator

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32. Electric Current in Conductors - Revision Facilitator

2008-11-06T02:38:00.000-08:00

Recollect some points for each topic and right click on the link to open it in a new window, read it, close it and come back here.

32.1 Electric current and current density
32.2 Drift speed
32.3 Ohm's law
32.4 Temperature dependence of resistivity
32.5 Battery and EMF
32.6 Energy transfer in an electric current
32.7 Kirchhoff's Laws
32.8 Combination of resistors in series and parallel
32.9 Grouping of batteries
32.10 Wheatstone bridge
32.11 Ammeter and Voltmeter
32.12 Stretched wire potentiometer
32.13 Chargin and discharging of capactiros
32.14 Atmospheric electricity

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33. Thermal and Chemical Effects of Electric Current - Revision Facilitator

2008-11-06T02:24:00.000-08:00

Recollect some points for each topic and right click on the link to open it in a new window, read it, close it and come back here.

33.1 Joule's law of heating
33.2 Verification of Joule's Laws
33.3 Seebeck effect
33.4 Peltier effect
33.5 Thomson effect
33.6 Explanation Seebeck, Peltier, Thomson effects
33.7 Electrolysis
33.8 Faraday's Laws of electrolysis
33.9 Voltameter or Coulomb meter
33.10 Primary and Secondary cells
33.11 Primary cells
33.12 Secondry Cell: Lead accumulator

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34. Magnetic Field - Revision Facilitator

2008-11-06T02:20:00.000-08:00

Recollect some points for each topic and right click on the link to open it in a new window, read it, close it and come back here.

1. Introduction
2. Definition of Magnetic field
3. Relation between electric and magentic fields
4. Motion of a charged aprticle in a uniform magentic field
5. Magnetic force on a current carrying wire
6. Torque on a current loop.

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35. Magnetic Field Due to a Current - Revision Facilitator

2008-11-06T02:12:00.000-08:00

Recollect some points for each topic and right click on the link to open it in a new window, read it, close it and come back here.

35.1 Bio Savart Law
35.2 Magnetic field due to current in a straight wire
35.3 Force between parallel currents
35.4 Field due to a circular current
35.5 Ampere's law
35.6 Magnetic field at a point due to a long straight current
35.7 Solenoid

Links will be created in due course.

Ch. 36 PERMANENT MAGNETS - Revision Facilitator

2008-11-06T02:10:00.000-08:00

38. Electro Magnetic Induction - Revision Facilitator

2008-11-05T03:36:00.000-08:00

Try to recollect and if required right click on the link, open in separate window and read. Close it and come back to this page.

38.1 Faraday's law,
38.2 Lenz's law;
38.3 The origin of induced emf
38.4 Eddy Current
38.5 Self and mutual inductance;
38.6 RC, LR and LC circuits with d.c. and a.c. sources.
38.7 Energy stored in an inductor
38.8 mutual inductance;
38.9 Induction coil

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Ch.43 Bohr's Model and Physics of the Atom

2008-11-05T03:06:00.000-08:00

43.1 Early atomic models
43.2 Hydrogen Spectra
43.3 Difficulties in Rutherford Model
43.4 Bohr's model
43.5 Limitations of Bohr's Model
43.6 The wave Function of an Electron
43.7 Quantum Mechanics of the Hydrogen Atom
43.8 Nomencluature in Atomic Physics
43.9 Laser

44. X-Rays - Revision Facilitator

2008-11-05T03:03:00.000-08:00

Try to recollect relevant points on the topic and if required right click on the topic if link is given and open in a new window to read the relevant material. Close the window and come back.

Production of X-rays

Continuous and Characteristic X-rays

Soft and Hard X-rays

Moseley's law

Bragg’s law

Properties of X rays

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JEE Physics Revision Facilitator - All Chapters Combined

2008-11-05T02:43:00.000-08:00

Have a quick review to recollect the material for each section.

1. Introduction to physics

1.1 What is Physics
1.2 Physics and Mathematics
1.3 Units
1.4 Definitions of base units
1.5 Dimension
1.6 Uses of dimension
1.7 Order of magnitude
1.8 The structure of world

2. Physics and mathematics

2.1 Vectors and scalars
2.2 Equality of vectors
2.3 Addition of vectors
2.4 Multiplication of a vector by a number
2.5 Subtraction of vectors
2.6 Resolution of vectors
2.7 DCT product or scalar product of two vectors
2.8 Cross product or vector product of two vectors
2.9 Differential calculus: dy/dx as rate measure
2.10 Maxima and Minima
2.11 Integral calculus
2.12 Significant digits
2.13 Significant digits in calculations
2.14 Errors in measurements

3. Rest and Motion: Kinematics

3.1 Rest and Motion
3.2 Distance and displacement
3.3 average speed and instantaneous speed
3.4 Average velocity and instantaneous velocity
3.5 Average accleration and instantaneous aceleration
3.6 Motion in a straight line
3.7 Motion in a plane
3.8 Projectile motion
3.9 Change of frame

4. The forces

4.1 Introduction
4.2 Gravitational forces
4.3 Electromagnetic (EM) forces
4.4 Nuclear Forces
4.5 Weak forces
4.6 Scope of Classical physics

5. Newtons laws of motion

5.1 Newton's First law
5.2 Newton's second law
5.3 Working with Newton's laws
5.4 Newton's third law of motion
5.5 Pseudo forces
5.6 The Horse and the cart
5.7 Inertia

6. Friction

6.1 Friction as the component of contact force
6.2 Kinetic friction
6.3 Static friction
6.4 Laws of friction
6.5 Understanding friction at atomic level
6.6 A Laboratory method to measure

7. Circular motion

7.1 Angular variables
7.2 Unit vectors along the radius and the tangent
7.3 Acceleration in circular motion
7.4 Dynamics of circular motion
7.5 Circular turnings and banking of roads
7.6 Centrifugal force
7.7 Effect of earth's rotation on apprarent weight

8. Work and energy

1. Kinetic enery
2. Work and work energy theorem
3. Calculation of work done
4. Work energy theorem for a system of particles
5. Potential energy
6. Conservative and nonconservative forces
7. Definition of Potential energy and conservation of mechanical energy
8. Change in the potential energy in a rigid body motion
9. Gravitational potential energy
10. Potential energy oif a compressed or extended spring
11. Different forms of energy: Mass energy equivalence

9. Centre of mass,linear momentum,collision

1. Centre of mass
2. Centre of mass of continuous bodies
3. Motion of the Centre of mass
4. Linear momentum and its conservation principle
5. Rocket propulsion
6. Collision
7. Elastic collision in one dimension
8. Perfectly inelastic collision in one dimension
9. Coefficient of restitution
10. Elastic collision in two dimensions
11. Impulse and impulsive force

10. Rotational mechanics

1. Rotation of a rigid body
2. Kinematics
3. Rotational dynamics
4. Torque of a force about the axis of rotation
5. Г = Iα
6. Bodies in equilibrium
7. Bending of a cyclist on a horizontal turn
8. Angular momentum
9. L = Iα
10. Conservation of angular momentum
11. Angular impulse
12. Kinetic energy of a rigid body rotating about a given axis
13. Power delivered and work done by a torque
14. Calculation of moment of inertia
15. Two important theorems on moment of inertia
16. Combined rotation and translation
17. Rolling
18. Kinetic energy of a body in combined rotation and translation
19. Angular momentum of a body in combined rotation and translation
20. Why does a rolling sphere slow down

Solutions of Problems in H C Verma's Books

2008-10-26T09:49:00.000-07:00

Today I bought the two books "Solutions of Concepts of Physics" containing solutions of problems in given in H C Verma's Books.

I am yet to use them but I recommend those books for purchase by JEE aspirants.

They are prepared by Govind Verma and published by Raj Publications, Darya Ganj, New Delhi 110002

One should try to do problems in the book and after spending some set time, should see the solution, if not able to do the problem.

Zeroth Law of Thermodynamics

2008-10-20T09:06:00.001-07:00

Zeroth law of thermodynamics

If two bodies A and B are in thermal equilibrium and A and C are also in thermal equilibrium then B and C are in also in thermal equilibrium

All bodies in thermal equilibrium are assigned equal temperature.

Heat flows from the body at higher temperature to the body at lower temperature

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Newton's Law of Motion -Videos

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Centre of mass - Linear momentum - Videos

Colliosions - Videos

Rotational Mechanics - Videos

Simple Harmonic Motion - Videos

http://knol.google.com/k/narayana-rao/rest-and-motion-kinematics-videos/2utb2lsm2k7a/4495

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COMPTON EFFECT

Schrodinger’s Equation

Ask questions and answer questions about IIT JEE Subjects

Transmutation of elements

Early Atomic Models

Thomson’s Model of the atom

Lenard's Suggestion on Atomic Structure

Hydrogen Spectra

Rutherford's Model

Difficulties with Rutherford’s Model

Bohr's Postulates and Model

Energy of an Hydrogen Atom

Radii of Different Orbit of Hydrogen Like Ion

Hydrogen Ion - Ground and Excited States

Hydrogen Spectra

Hydrogen Spectra - Series Structure

Ionization Potential

Binding Energy

Excitation potential

Limitations of Bohr Model

Quantum Mechanics of the Hydrogen Atom

Production of X-rays

Continuous and Characteristic X-rays

Soft and Hard X-rays

Moseley's law

Bragg’s law

Properties of X rays

Atomic nucleus

Nuclear Forces

Binding Energy

Radioactive decay

Law of Radioactive decay;

Decay constant;

Half-life and Mean life;

Properties and Uses of Nuclear Radiation

Binding energy and its calculation

Nuclear Fission

Uranium Fission Reactor

Nuclear Fusion