Thursday, February 7, 2008

IIT JEE Physics Formula Revision 42. Photoelectric Effect and Waveparticle Duality

1. Relation between properties of photon and properties of light waves.

E and p are energy and linear momentum of a photon of light.
ν and λ are the frequency and wavelength of the same light when it is considered (behaves) as a wave.

Then E = hν = hc/λ
p = h/λ = E/c ... (42.1)

wherein h is a universal constant known as the Planck constant and has a value 6.626*10^-34 J-s and is also equal to 4.136*10^-15 eV-s.

C = velocity of light vacuum = 299,792,458 m/s ≈ 3.0*10^8 m/s


2. The maximum kinetic energy of the electron that comes out due to energy E supplied is:

Kmax = E – φ

Some energy from the E – φ is dissipated as the electron may have some collision before escaping from the material.

If monochromatic light of wave length is incident on the metal surface, photons of energy hc/ λ fall on the surface. The maximum kinetic energy of an electrons that comes out due to these photons is:

Kmax = hc/λ - φ = h υ - φ

The above equation is called Einstein's photoelectric equation.

3. Writing work function φ as hυ0 (h multiplied by frequency)

υ λ = c
υ0 = c/ λ0
λ0 = threshold wavelength

Kmax = h(υ - υ0)


4. Relation between Maximum kinetic energy of photoelectrons and stopping potential:

As a photoelectron travels from the cathode to the anode, the potential energy increases by eV0. This is equal to the decrease in the kinetic energy of the photoelectron.

The maximum kinetic energy a photoelectron will have is hc/λ - φ
Hence eV0. = hc/λ – φ

V0 = hc/e(1/ λ) – φ/e

5. A relation for wavelength of electron was proposed by Louis Victor de Broglie.

The proposed expression for wavelength is

λ = h/p

Where p is the momentum of the electron and
h is the Planck constant.

IIT JEE Physics Formula Revision 43. Bohr's Model and Physics of Atom

1. Equation for wavelengths of radiation emitted by the hydrogen atom.
1/λ = R [1/n² - 1/m²]

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

2. Velocity of an electron when it is in a stationary orbit represented by n which is an integer

v = Ze²/2 ε0hn


3. Radius of a stationary orbit based on n which is an integer

r = ε0h²n²/πmZe²


4. Kinetic energy when electron is in nth orbit is

K = ½ mv² = mZ²e4/8 ε0²h²n²


5. 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.



6. The total energy of the atom is

E = K+V = - mZ²e4/8 ε0²h²n²


7. For a hydrogen like ion with Z protons in the nucleus,

rn = radius of ‘n’ th orbit = n²a0/Z

8. Energy of hydrogen atom when the single electron is in the nth orbit.
En = E1/n² = -13.6/n² eV

-13.6 eV is the energy when the electron is in the n = 1 orbit.

Note that the energy is expressed in negative units, so that larger magnitude means lower energy.

9. If an electron jumps from mth orbit to nth orbit (m>n) of a hydrogen like ion, 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]

10. 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.


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


En = - mZ²e4/8 ε0²h²n²

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

ψ(r,) = ψ100 = √(Z³/ π a0²) *(e-r/ a0)

where
ψ100 denotes that n =1, l = 0 and ml = 0

a0 = Bohr radius

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IIT JEE Physics Formula Revision 44. X-Rays

1. K = eV
where K = Kinetic energy of an electron when it hits the target
V = potential difference applied between the target and the filament

2. λ = hc/E

Where
λ = wave length of the X-ray
E = kinteic energy of the electron due to which the X-ray is emitted


3. λmin = hc/eV

λmin = cutoff wavelength below which no X-rays are emitted
V = potential difference applied between the target and the filament

4. Moseley's law

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

√(ν) = a(Z-b)

where
ν = frequency of X-rays
Z = position number of element.
a and b are constants

5. Bragg’s law

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

IIT JEE Physics Formula Revision 46. Nucleus

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

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

2. B = [Zm{11H} +Nmn
– m{ Z Z+n}]c²

Where
B = binding energy of the nucleus

m{11H} is the mass of a hydrogen atom

m{ Z Z+n} is the mass of an atom with Z protons and N neutrons


3. Binding energy per nucleon = B/A = a1 - a2/(A1/3) - a3Z(Z-1)/ (A4/3)


4. Mass excess =
(mass of atom – A’)c²

5. Mass excess = 931(m-A)MeV

6. Alpha decay process is represented by

ZAX --> Z-2A-4Y + 24He

7. q value of the process

Q = [m{ZAX} – m{Z-2A-4Y} – m{24He}]c²

8. Beta decay process

N --> p + e + antineutrino

9. Beta decay proces
ZAX --> Z+1AY +e + antineutrino

e is also shown as beta minus.

10. kinetic energy Q available ot the product particles is

Q = [m(ZAX – m{Z+1AY}]c²

11. Proton conversion process – Beta plus decay

P --> n + e+ + v (neutrino)



12.
ZAX --> Z-1AY + e+ + v (neutrino)

13.Q value of the decay

Q = {m(ZAX) – m(Z-1AY) – 2me]c²

IIT JEE Study of Physics

As I have brought my Chemistry study to some stage, I started looking at physics once again. I am trying to write down formulas of each chapter in a notebook first. That way I read the chapter fully. It may take two days for each chapter. I may start the posting the formulas for revision purpose in this blog. Along with it I plan to go through problems/questions of past JEEs and update the study guides with them.

Tuesday, January 29, 2008

IIT JEE 2008 Syllabus Physics - H C Verma Sections

General:
Units and dimensions 1.3, 1.5,
dimensional analysis;
least count,
significant figures 2.12;
Methods of measurement and
error analysis (2.14) for physical quantities pertaining to the following experiments: Experiments based on using Vernier calipers and screw gauge (micrometer),

Determination of g using simple pendulum, Young’s modulus by Searle’s method, Specific heat of a liquid using calorimeter, focal length of a concave mirror and a convex lens using u-v method, Speed of sound using resonance column, Verification of Ohm’s law using voltmeter and ammeter, and specific resistance of the material of a wire using meter bridge and post office box.

Mechanics:
Kinematics in one and two dimensions (Cartesian coordinates only),
projectiles 3.8;
Uniform Circular motion 7.3;
Relative velocity.
Newton’s laws of motion 5.1,5.2,5.4;
Inertial and uniformly accelerated frames of reference 5.7;
Static and dynamic friction 6.2, 6.3;
Kinetic and potential energy 8.1, 8.5;
Work and power;
Conservation of linear momentum and mechanical energy.
Systems of particles;
Centre of mass and its motion 9.1, 9.3;
Impulse 9.11;
Elastic and inelastic collisions 9.6,9.7,9.8.
Law of gravitation;
Gravitational potential and field;
Acceleration due to gravity;
Motion of planets and satellites in circular orbits;
Escape velocity.
Rigid body,
moment of inertia,
parallel and perpendicular axes theorems,
moment of inertia of uniform bodies with simple geometrical shapes;
Angular momentum 10.8;
Torque;
Conservation of angular momentum 10.9;
Dynamics of rigid bodies with fixed axis of rotation 10.1, 10.3;
Rolling without slipping of rings, cylinders and spheres 10.17;
Equilibrium of rigid bodies;
Collision of point masses with rigid bodies.

Linear simple harmonic motion 12.1 and
angular simple harmonic motion 12.7.

Hooke’s law 14.5,
Young’s modulus 14.5, 14.8

Pressure in a fluid 13.2;
Pascal’s law 13.3;
Buoyancy 13.5;
Surface energy 14.10 and surface tension 14.9,
capillary rise 14.14;
Viscosity (Poiseuille’s equation excluded) 14.15,
Stoke’s law 14.17;
Terminal velocity 14.18,
Streamline flow 13.7,
equation of continuity 13.10,
Bernoulli’s theorem and its applications 13.11, 13.12.

Wave motion (plane waves only) 15.1,
longitudinal and transverse waves 15.13, 15.14,
superposition of waves;
Progressive and stationary waves;
Vibration of strings and air columns;
Resonance;
Beats;
Speed of sound in gases 16.4;
Doppler effect (in sound) 16.13.

H C Verma Volume 2

Thermal physics:
Thermal expansion of solids, liquids and gases 23.10;
Calorimetry 25.3,
latent heat25.6,25.7,25.8;
Heat conduction in one dimension;
Elementary concepts of convection and radiation;
Newton’s law of cooling 28.11;
Ideal gas laws 24.7;
Specific heats (Cv and Cp for monoatomic and diatomic gases)27.1,27.2,27.3,27.4,;
Isothermal and adiabatic processes 27.5 27.6, 27.7,,
bulk modulus of gases;
Equivalence of heat and work;

First law of thermodynamics and its applications (only for ideal gases) 26.1;
Blackbody radiation 28.7:
absorptive and emissive powers;
Kirchhoff’s law 28.8;
Wien’s displacement law,
Stefan’s law 28.10.

Electricity and magnetism:
Coulomb’s law 29.2;
Electric field and potential 29.3, 29.6,29.8;
Electrical potential energy of a system of point charges and of electrical dipoles in a uniform electrostatic field 29.5 29.7,29.9;
Electric field lines 29.13;
Flux of electric field 30.1;
Gauss’s law 30.3 and

Gauss's law's application in simple cases, such as, to find field due to infinitely long straight wire, uniformly charged infinite plane sheet and uniformly charged thin spherical shell 30.4, 30.5.

Capacitance 31.1;
Parallel plate capacitor with and without dielectrics 31.5,31.7,;
Capacitors in series and parallel 31.3;
Energy stored in a capacitor.

Electric current;
Ohm’s law 32.3;
Series and parallel arrangements of resistances and cells 32.8;
Kirchhoff’s laws and simple applications;
Heating effect of current 33.1, 33.2.
Biot–Savart’s law 35.1 and
Ampere’s law 35.5;
Magnetic field near a current-carrying straight wire, along the axis of a circular coil and inside a long straight solenoid 34.2,34.5, 35.2,35.635.7;

Force on a moving charge and on a current-carrying wire in a uniform magnetic field 34.4, 34.5.

Magnetic moment of a current loop 34.6;
Effect of a uniform magnetic field on a current loop 34.6;
Moving coil galvanometer 36.9, voltmeter, ammeter and their conversions 39.9.

Electromagnetic induction:
Faraday’s law 38.1,
Lenz’s law 38.2;
Self and mutual inductance 38.5,38.8;
RC, LR and LC circuits with d.c. and a.c. sources 38.6.


Optics: Rectilinear propagation of light; Reflection and refraction at plane and spherical surfaces; Total internal reflection; Deviation and dispersion of light by a prism; Thin lenses; Combinations of mirrors and thin lenses; Magnification.

Wave nature of light: Huygen’s principle, interference limited to Young’s double-slit experiment.

Modern physics:
Atomic nucleus 46.1;
Alpha, beta and gamma radiations 46.4, 46.6;
Law of radioactive decay 46.4,46.5;
Decay constant;
Half-life and mean life 46.5;
Binding energy and its calculation 46.3;
Fission 46.8, and
fusion processes 46.10;
Energy calculation in these processes.

Photoelectric effect 42.2;
Bohr’s theory of hydrogen-like atoms 43.4,43.5;
Characteristic and continuous X-rays 44.1, 44.2,44.6,
Moseley’s law 44.4;
de Broglie wavelength of matter waves.

Wednesday, January 2, 2008

IIT JEE 2008 Syllabus Physics

General: Units and dimensions, dimensional analysis; least count, significant figures; Methods of measurement and error analysis for physical quantities pertaining to the following experiments: Experiments based on using Vernier calipers and screw gauge (micrometer),

Determination of g using simple pendulum, Young’s modulus by Searle’s method, Specific heat of a liquid using calorimeter, focal length of a concave mirror and a convex lens using u-v method, Speed of sound using resonance column, Verification of Ohm’s law using voltmeter and ammeter, and specific resistance of the material of a wire using meter bridge and post office box.


Mechanics: Kinematics in one and two dimensions (Cartesian coordinates only), projectiles; Uniform Circular motion; Relative velocity.
Newton’s laws of motion;
Inertial and uniformly accelerated frames of reference;
Static and dynamic friction;
Kinetic and potential energy;
Work and power; Conservation of linear momentum and mechanical energy.
Systems of particles;
Centre of mass and its motion;
Impulse; Elastic and inelastic collisions.
Law of gravitation; Gravitational potential and field; Acceleration due to gravity; Motion of planets and satellites in circular orbits; Escape velocity.
Rigid body, moment of inertia, parallel and perpendicular axes theorems, moment of inertia of uniform bodies with simple geometrical shapes; Angular momentum; Torque; Conservation of angular momentum; Dynamics of rigid bodies with fixed axis of rotation; Rolling without slipping of rings, cylinders and spheres; Equilibrium of rigid bodies; Collision of point masses with rigid bodies.

Linear and angular simple harmonic motions.
Hooke’s law, Young’s modulus
Pressure in a fluid; Pascal’s law; Buoyancy; Surface energy and surface tension, capillary rise; Viscosity (Poiseuille’s equation excluded), Stoke’s law; Terminal velocity, Streamline flow, equation of continuity, Bernoulli’s theorem and its applications.
Wave motion (plane waves only), longitudinal and transverse waves, superposition of waves; Progressive and stationary waves; Vibration of strings and air columns;Resonance; Beats; Speed of sound in gases; Doppler effect (in sound).


Thermal physics: Thermal expansion of solids, liquids and gases; Calorimetry, latent heat; Heat conduction in one dimension; Elementary concepts of convection and radiation; Newton’s law of cooling; Ideal gas laws; Specific heats (Cv and Cp for monoatomic and diatomic gases); Isothermal and adiabatic processes, bulk modulus of gases; Equivalence of heat and work;

First law of thermodynamics and its applications (only for ideal gases); Blackbody radiation: absorptive and emissive powers; Kirchhoff’s law; Wien’s displacement law, Stefan’s law.

Electricity and magnetism: Coulomb’s law; Electric field and potential; Electrical potential energy of a system of point charges and of electrical dipoles in a uniform electrostatic field; Electric field lines; Flux of electric field; Gauss’s law and its application in simple cases, such as, to find field due to infinitely long straight wire, uniformly charged infinite plane sheet and uniformly charged thin spherical shell.

Capacitance; Parallel plate capacitor with and without dielectrics; Capacitors in series and parallel; Energy stored in a capacitor.

Electric current; Ohm’s law; Series and parallel arrangements of resistances and cells; Kirchhoff’s laws and simple applications; Heating effect of current.
Biot–Savart’s law and Ampere’s law; Magnetic field near a current-carrying straight wire, along the axis of a circular coil and inside a long straight solenoid; Force on a moving charge and on a current-carrying wire in a uniform magnetic field.

Magnetic moment of a current loop; Effect of a uniform magnetic field on a current loop; Moving coil galvanometer, voltmeter, ammeter and their conversions.
Electromagnetic induction: Faraday’s law, Lenz’s law; Self and mutual inductance; RC, LR and LC circuits with d.c. and a.c. sources.


Optics: Rectilinear propagation of light; Reflection and refraction at plane and spherical surfaces; Total internal reflection; Deviation and dispersion of light by a prism; Thin lenses; Combinations of mirrors and thin lenses; Magnification.

Wave nature of light: Huygen’s principle, interference limited to Young’s double-slit experiment.

Modern physics: Atomic nucleus; Alpha, beta and gamma radiations; Law of radioactive decay; Decay constant; Half-life and mean life; Binding energy and its calculation; Fission and fusion processes; Energy calculation in these processes.
Photoelectric effect; Bohr’s theory of hydrogen-like atoms; Characteristic and continuous X-rays, Moseley’s law; de Broglie wavelength of matter waves.