## Wednesday, May 20, 2015

### Concept Review - Chapter 2 Physics and Mathematics

Scalars

Vectors

Equality of vectors

Magnitude of av+bv = SQRT(a²+b²+ 2ab cos θ)

The angle of the resultant with av is α where
tanα = b sin θ/(a+b cos θ)

Interesting point to make note of:
Two vectors having equal magnitudes of a make an angle θ with each other. Find the magnitude and direction of the resultant(Resultant is output of the addition of two vectors.)

Magnitude = 2a cos θ/2
and
tan α = a sin θ/(a + a cos θ) = (2asin(θ/2)cos(θ/2))/(2acos²(θ/2))
= tan (θ/2)

Example: Two vectors are of equal magnitude of 10 units. One of them is inclined at 45° to the X-axis and the other is inclined at 75° to the X-axis. Find the magnitude and direction of the resultant with respect to X-axis.

The angle between vectors is 30°.
Hence magnitude of the resultant will be 20 cos 15°
The direction - The resultant is inclined at 60° to the X axis.

Subtraction of vectors

Multiplication of vector by a number

2.6 Resolution of vectors

2.7 Dot product or scalar of two vectors

2.8 Cross product or vector product of two vectors

Zero vector

2.9 Differential Calculus

Concepts form Calculus

dy/dx as rate measure

2.10 Maxima and minima

2.11 Integral Calculus

2.12 Significant digits

2.14 Errors in measurement
In recording measurements in experiments, several errors can occur. The equipment can be set in a faulty manner, and experimenter can make errors. These errors can be corrected by supervisors and trainers. But still some errors are committed due to random noncontrollable causes.

As random errors are sometime positive and sometimes negative, average is considered as true value. But sigma or standard deviation of the measurements can be calculated and 1.96 sigma limits and 3 sigma limits can be determined to specify confidence limits for true value. But at least 8 measurements are to be taken to get a good statistical estimate for average and standard deviation.

Update 20 May 2015
Earlier update 7 May 2008

## Sunday, May 10, 2015

### JEE Physics Blogs - LIfe Time Visitors and Page Views - 11 May 2015

I was happy to see today the site performance as reported by site meter

Learning Physics for IIT JEE
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http://www.sitemeter.com/?a=stats&s=s37iitjeeph

## Friday, February 27, 2015

### Physics Prize for Narayana Rao - Intermediate 1971

The Justification for My writing this blog. I have a responsibility to the society to share something that I have learned in the way I think will facilitate learning.

## Saturday, January 31, 2015

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

5. Newtons laws of motion
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

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

22. Photometry

23. Heat and Temperature
Study Guide and Revision Notes

24. Kinetic theory of Gases
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

29. Electric Field and Potential
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

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

45. Semiconductors and Semiconductor Devices

46. Nucleus
Study Guide and Revision Notes

47. The Special Theory of Relativity

## Tuesday, January 6, 2015

### January - History of Physics

http://www.aps.org/publications/apsnews/features/history.cfm

January 2, 1839: First Daguerreotype of the Moon
http://www.aps.org/publications/apsnews/201301/physicshistory.cfm

28 - The Challenger Explosion
http://www.aps.org/publications/apsnews/200101/history.cfm

Micrographia by Robert Hooke first appeared in bookshops in January 1665.  For scientists, it provided not only a wealth of new data but an articulate and beautifully presented justification for experimental science. Every one of the 60 observations in the Micrographia are detailed starting points for further physical investigations, accompanied by 58 stunning engravings.
http://www.aps.org/publications/apsnews/200201/history.cfm

Birthdays for January:
1: Satyendranath Bose (1894)
8: Stephen Hawking (1942)
22: André Marie Ampère (1775); Lev D. Landau (1908)
23: David Hilbert (1862); Hideki Yukawa (1907)
25: J. L. Lagrange (1736)