CSS 2025 Physics Combined Papers Past Paper

Paper details

Examination

CSS

Year

2025

Subject

Physics

Paper

Combined Papers

Subject type

Optional

Mode

Subjective

Questions recorded from this paper

These 12 question wordings are transcribed from CSS Vista’s structured Physics past-paper record for CSS 2025.

1. Q3 · Mechanics(a) Differentiate between Fermi-Dirac, Bose-Einstein and Maxwell- (10) Boltzman’s statistics. (b) What do you understand by classical statistical mechanics and quantum (6) statistical mechanics? (c) A 0.5m3 vessel is filled with air at atmospheric pressure. The air is (4) (20) churned by a paddel wheel attached to a shaft 0.1m in diameter, rotating at a speed of 1800 rpm. A force of 5.0N acts on the rim of the shaft. What would be the pressure in the vessel after 10 sec of operation?
2. Q2 · Gradient(a) State and prove Stoke’s theorem. (10) (b) Prove that if the vector is the gradient of a scalar function then its line (6) integral around a closed curve is zero. (c) A particle moves along the curve x = 2t2 , y = t2 - 4t , z = 3t-5 where t is (4) (20) the time. Find the components of its velocity and acceleration at time t=1 in the direction 2i-3j+2k
3. Q8 · ReflectionWrite Comprehensive notes on any two of the following: (10 each) (20) (a) Newton’s ring (b) Polarization by reflection (c) Doppler effect ` Roll Number
4. Q5 · Interference(a) Discuss analytical treatment of interference of light to calculate intensity (10) in double slit interference. Describe the conditions of maximum and minimum intensity and also draw the intensity pattern for double slit interference. (b) What is resolving power of a grating? Show that it increases with the order (6) of image. (c) A body having SHM has an amplitude of 5cm, and a period of 0.2s. When (4) (20) the displacement is 5cm, find the acceleration and velocity.
5. Q6 · Heat and Thermodynamics(a) What is Carnot Cycle? Draw and explain it for a reversible process. (10) (b) What does Gibbs function describe? Prove that Gibbs function for a (6) reversible isothermal and isobaric process is constant. (c) A heat engine absorbs 52.4 kJ of heat and exhausts 36.2 kJ of heat in each (4) (20) cycle. Calculate efficiency of heat engine and work done by engine per cycle.
6. Q7 · Heat and Thermodynamics(a) Derive Clausius – Claypron equation and also write its two conclusions. (10) ɣ-1 (6) (b) Prove that TV =constant (c) Air occupying 0.142 m3 at 2.04x105 is expanded isothermally to 1 atm and (4) (20) then cooled at constant pressure until it reaches its initial volume. Find work done on the gas.
7. Q4 · temperature(a) What is viscosity? Discuss effect of temperature on the viscosity of liquids (10) and gases. (b) Explain why the level of mercury is down in capillary when placed in (6) container of mercury, while it is up in the capillary in case of water? (c) A garden hose has an inside diameter of 2 cm and water flows through it is (4) (20) at 3 m/s. (i) What nozzle diameter is required for the water to emerge at 10 m/s? (ii) At what rate does the water leave the nozzle?
8. Q5 · Modern and Quantum Physics(a) Derive the expression for electric dipole moment. Discuss two uses in modern science. (10) (b) Discuss Biot and Savart law and derive its expression, using suitable schematic figure. (10) (20)
9. Q6 · Modern and Quantum Physics(a) Explain how Hall’s effect could be used to find the sign of charge carriers. (10) (b) Explain the Hall’s effect. How it could calculate the number of charge carriers in (10) (20) material.
10. Q7 · Modern and Quantum Physics(a) Explain the construction and working of photo multiplier tube (PMT). (10) (b) Compare the energies of a proton and electron having same De Broglie wave length of (10) (20) 1A.
11. Q3 · observables(a) In quantum mechanics explain the term commutation between the observables. (10) (b) Explain how De Broglie wave particle duality laid down the fundamentals of (10) (20) uncertainty principle.
12. Q8 · Heisenber's uncertainty relationship and indeterminacy based on commutation properties of operatorsWrite short notes any TWO of the following: (10 each) (20) (a) Reduced mass correction in spectroscopy (b) Electron microscope (c) Heisenberg uncertainty principal

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