BSc Physics SEM III ATKT PHYSICS PAPER I Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate maximum marks

1. Q1 A) Select correct answer 1 A body is moving in a circular orbit. Its angular momentum at a point is 12 marks
   • a) radial b) tangential perpendicular to the plane of orbit
   • d) in the plane of orbit 2 The time in which the amplitude of a damped harmonic oscillator decays to 1/e of its original value is called
   • a) time period b) damping time c) relaxation time d) none of the above engine absorbs heat at 1000 K and rejects heat at 600 K. If the engine operates at maximum possible efficiency the work done by the engine at 2000 J input is 4 thermal efficiency of all reversible engines working between the same two temperature limits are
   • a) the same b) different c) zero d) 100% engine has compression ratio from
   • a) 6 to 10 b) 10 to 15. 15 to 20 d) 25 to 40 6 Joule-Thomson effect, if — bis positive then after expansion, the
   • B) Answer in one sentence 1 State the expression for displacement of damped harmonic oscillator 3
   • 2. Give the property used to define the Kelvin’s absolute scale of What is the entropy of an ideal crystal at absolute zero temperature? An oscillator returns to its equilibrium state in the shortest time when it is
   • 2. Time period of a compound pendulum about centre of suspension and centre of oscillation is 3 The is a system operating in a cyclic process that converts heat into work 4 two or more engines operate between the same source but different sinks the one operating with the highest temperature difference will have 5 Otto engine is used as a working substance
2. Q2 A) Attempt any one that energy of a damped harmonic oscillator decreases exponentially with time as E(t) = 2 the expression of amplitude and phase angle in steady state term of forced damped harmonic oscillator. Discuss amplitude and phase at 8 marks
   • B) Attempt any one What is meant by internal and external forces? Derive law of conservation of linear momentum for a system of particles clearly mentioning the assumptions made 2 Obtain the expression of time period for compound pendulum. Hence obtain the minimum and maximum time period for it 8
   • C) Attempt any one particles system have position vectors in metres specified by masses of the particles are 2 kg each, find the centre of mass of the Write a short note on Quality Factor of damped harmonic oscillator 4
3. Q3 A) Attempt any one State the Clausius theorem and prove it Draw the p— V diagram of a Carnot cycle and explain each of the four 8 marks
   • B) Attempt any one 8
   • 1. Obtain expressions for entropy change in an ideal gas in different Show that the Kelvin — Planck and Clausius statements of second law of thermodynamics are logically equivalent
   • C) Attempt any one why it is not possible to have negative temperatures on the thermodynamic scale of temperature 2 Calculate the change in entropy if 10 g of water is heated from 313 K to 353 K. Given:- specific heat of water = 1 cal/g - K 4
4. Q4 A) Attempt any one is Joule-Thomson effect? Explain the theory behind the porous plug experiment and show that it is an isenthalpic process 2 third law of thermodynamics. Explain any two consequences of it 8 marks
   • B) Attempt any one Maxwell’s equations derive the Clausius-Clapeyron’s equation and discuss the effect of pressure on the boiling point and melting point of a 2 With the help of PV diagram explain the step by step working of a diesel 8
   • C) Attempt any one 1 Using Maxwell’s thermodynamic relation, show that for a perfect gas 2 Calculate the inversion temperature of hydrogen and helium if the critical temperature of hydrogen and helium are 29 K and 5.2 K respectively Attempt any Four (20) 1 What is centre of oscillation and centre of suspension for compound pendulum? Show that time period about them are equal 4
   • 2. Show that resonance in a forced damped harmonic oscillator occurs at a frequency slightly less than natural frequency From the expression for efficiency of a Carnot engine show that lowering the temperature of the sink is in increasing its efficiency 4 Write a short note on reversible processes Distinguish between Otto engine and Diesel engine 6 Calculate under what pressure water will boil at if the change in specific volume when | gram of water is converted to steam is 1676 cm’ (Given:- Latent heat of steam = 540 cal/g, J = 4.2 x ergs/cal and 1

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