Name of the Organization : Haryana Public Service Commission
Name of the Exam : HCS (Ex.Br.) Main Exam
Subject : Physics
Document Type : Previous Question Paper
Year : 2014
Website : http://hpsc.gov.in/en-us/
Download Sample/Model Question Paper : https://www.pdfquestion.in/uploads/11144-Physics.pdf
HCS Main Exam Physics Question Paper :
Physics :
Code.No : 16
Time : 3 Hours
Max.Marks : 150
Related : HPSC HCS Main Exam Mechanical Engineering Question Paper : www.pdfquestion.in/11141.html
Note:
** Attempt five questions. All questions carry equal marks. Question number I is compulsory.
** Answer any two questions from part I and two questions from part II.
** The parts of the same questions must be answered together and must not be interposed between answers to other questions.
** In case of any discrepancy in the English and Hindi versions, English version will be taken as final.
l. Attempt any four of the following :
a. Write down and explain Bernoulli’s equation. Using this equation discuss the principle of the lift of an Airplane.
b. Describe the principle of participation of energy in thermodynamics. Using this principle, discuss about the spccific heat of diatomic molecules.
c. Write a short note on the principle of holography.
d. Find out the value of current flowing through and the potential difference across each resistance and also E, in the following circuit. Assume internal resistance of the two cells to be negligible.
e. Give a classification of the following fundamental particles photons, Also state which of these are stable and which ones have finite lifetime.
f. Identify the following Ga1e. Give its truth table and explain the same.
2. (a) Aman whose mass is 90 kg is in a lift ( elevator). Determine the force the floor of the lift exerts on him when
( i ) the lift goes up with a uniform speed,
(ii) the lift accelerate up to 3 ms-‘ and
iii; the cable of the lift brakes and the lift falls freely.
(b) Consider two frames of reference S’ and S and assume S’ to be moving with respect lo S along x-axis with a velocity v. Using Lorentz Transformation for position coordinates and time, obtain expression for velocity of a body as measured in S ‘ in terms of that measured in S.
c) Consider two observers O and O’ such that frame of reference attached to O’is rotating with an angular velocity O) with respect to the same attached to O. certain appropriate expressions for acceleration of a particle as observed by O in terms of that by O’ .
3. (a) What is a Carnot cycle? Deduce an expression temperature T1, and Sink temperature T2.
(b) Make a qualitative sketch of Maxrvellian distribution of velocities of gas molecules at two temperatures T, and T, (assume T, > T,). Deduce expression for root mean square velocity and calculate the same for H. gas (given k : 1.38 X 10″ J/K and m, : 1.6?4X10″ kg;.
c) Using De bye model, obtain an expression for specific heat (at constant volume) of solids for temperatures much below De by temperature.
4. (a) Assume a particle of mass m subjected to an elastic force and a velocity dependent damping force. Let this b applied upon by a force F focus. Set up the equation of motion for the particle (solution is not required). Write down the expression for velocity amplitude of the oscillator (no derivation is required). At which frequency of the applied force does the energy resonance occur ?
b) Two transverse of simple harmonic waves A and B (of same frequency) of amplitudes 5 units and 2 units superpose with phase difference (1) nl2 and (ii) ru. Obtain ratio of the intensities of the superposed patterns.
c) A diffraction grating of width 2 cm and having 20,000 lines is used in the third order in range of wavelength 55004. What is the smallest frequency interval (in cm ‘ units) that the grating can resolve?
(d) State two special characteristics of the LASER source in relation to an ordinary light source. Briefly explain how they are achieved in a LASER source.