Physics Paper (I) 2015

FEDERAL PUBLIC SERVICE COMMISSION
COMPETITIVE EXAMINATION FOR RECRUITMENT TO POSTS
IN BS-17, UNDER THE FEDERAL GOVERNMENT, 2015
PHYSICS, PAPER-I
TIME ALLOWED: THREE HOURS (PART-I MCQs) Maximum Marks: 20

PART I (MCQs) Maximum 30 Minutes (PART-II) Maximum Marks: 80

Note: (i) Part-II is to be attempted on the separate Answer Book.
(ii) Attempt ONLY FOUR questions from PART-II. All questions carry EQUAL Marks.
(iii) All the parts (if any) of each Question must be attempted at One Place instead of at different places.
(iv) Candidate must write Q. No. in the Answer Book in accordance with Q. No. in the Q. Paper.
(v) No Page /Space be left blank between the answers. All the blank pages of Answer Book must be crossed.
(vi) Extra attempt of any question or any part of the attempted question will not be considered.

PART-II
Q. 2. (a) How does a vector quantity from a scalar quantity?
(b) A small airplane leaves an airport on an overcast day and is later sighted 215 km away in a direction making an angle of 22° east of north. How far cast and north is the airplane from the airport when sighted?
(c) Explain the conservation of momentum and angular momentum.
Q.3. (a) Describe Michelson-Morley experiment and show how negative results obtained from this experiment were interpreted?
(b) What is time dilation in relativity? Obtain an expression for time dilation regarding time interval between two events measured from two different inertial frames.
Q.4. (a) What is length contraction in special theory of relativity?
(b) What are isothermal and changes? Explain with volume pressure diagram.
(c) Define the term Coherence. Drive an Expression for the Coherence length of a wave train that has a frequency bandwidth bandwidth .
Q.5. (a) Explain the formation of rings and show that the radii of mth dark ring is proportional to the under root of wavelength.
(b) What is diffraction grating? Define grating element. Explain how a plane transmission grating is used to determine the wavelength of light.
Q.6. (a) What is a LASER? Explain with neat diagram the process of absorption of light, spontaneous emission and stimulated emission of light.
(b) Explain with the help of level diagram how stimulated emission results from electron impact of He-Ne Gas LASER?
(c) Explain how the viscosity of a given liquid is determined using Stokes's method experimentally?
Q.7. (a) Distinguish between the power and the magnifying power of a Telescope:
(b) Discuss the applications of Law of Theunodynamics.
(c) Describe the Galileos of relativity.
Q.8. (a) Briefly discuss FOUR of the following terms:
(a) Standing waves (b) Dopplers effect
(c) Electromagnetic (d) Surface tension
(e) Components of vectors