HCS physics optional question paper 2011 Frontier IAS
Baljit Dhaka
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HCS physics optional question paper 2011 Frontier IAS

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HCS physics optional question paper 2011

HCS Mains-2011 Physics (Code-16)

Time: 3 Hours  Maximum Marks: 150

NOTE: Attempt FIVE questions in all. All questions carry equal marks, i.e. 30. Q.No.1 is compulsory.

Answer any two questions from Part-I and any two questions from Part-II. The parts of the same question must be answered together and must not be interposed between answers to other questions.

1.Write short notes on any FOUR of the followings: (4x7.5) 

(a) Coriolis force

(b) Wein’s law

(c) Ruby laser

(d) Ferromagnetic materials

(e) Compton effect

(f) Intrinsic & extrinsic semiconductors


2.(a) What is a central force? Give an example. How will you ?nd out if a given force is central or not? (15)

(b) Two particles of the same mass are moving along a straight path with velocity V1 and V2 respectively.

Show that the momentum of the system in the centre of mass system is zero. (10)

(c) Explain brie?y the objective of Michelson-Morley experiment. (05)


(a) State and explain Stefan’s law of black body radiation. (05)

(b) The surface of a furnace is at a temperature of 1427 centigrade. If the Stefan’s constant is 5.7 * 10-8  W/m2 /k  and assuming furnace surface to be a black body, how much heat is radiated by 2 m2  of The surface in 1 hour? . (15)

(c) Assuming Maxwell —Boltzmann distribution of velocities to hold, what is the relation between the root-

mean-square and the average speed of molecules of a gas? What is the relation between the average

speed and the most probable speed? (10)

4.(a) Show that superposition of two mutually perpendicular SHMs of equal amplitude and phase

differences of 900 is a circular motion. (10)

(b) Obtain expression for the resolving power of a grating.  (10)

(c) A particle executes SHM with a frequency of 2Hz and amplitude 0.05m. Calculate the maximum and the

 minimum magnitudes of the acceleration. (10)


  1. (a) A conducting hollow sphere of radius R1 meter is concentrically surrounded by another conducting

hollow sphere of radius R2  meter. The charges on the two spheres are ql and q; coulomb respectively.

What is the electrostatic potential at a distances x (R1 < x < R2) from their common centre? (9)

(b) What is power factor of an alternating circuit? How much is its value for an LCR series circuit at

resonance? (6)

(c) A current carrying circular coil is of radius R. Calculate the ratio of the magnetic induction at the centre

of the coil and at a point a distance R from the centre and on the axis of the coil. (15)

  1. (a)Photons of energy 3.0eV fall on a photoelectron emitter of work function 2.5 eV. The emitted electrons

are subjected to a transverse uniforms magnetic ?eld of induction B. Calculate the minimum value of B

so that all emitted electrons move in circles of radii less than 0.1 m (20)

(b)De?ne decay constant, activity and mean life with reference to radioactive decay. Also de?ne a Curie. (10)

 7. (a) Explain brie?y the mechanism of development of built-in potential barrier during the formation of

a p-n junction. (10) 

(b) Draw the common- emitter output characteristics of a transistor and identify its different regions of

operation. In which regions it works as an ampli?er? Explain.  (15)

 (c) Write the truth-tables for AND & OR gates. (05)