CSS 2023 Physics Combined Papers Past Paper

Paper details

Examination

CSS

Year

2023

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 2023.

1. Q2 · Gradient(a) What is Gradient of a scalar function? Give its physical significance and show (10) that ����������⃗ Gradφ = �∇⃗. φ (b) Define the term ‘acceleration’ and find its Cartesian components. (06) (c) If A⃗ = xz 3 ı̂ − 2x 2 zȷ̂ + 2yz 4 k�, then find curl of A at the point (1,-1,1) (04) (20)
2. Q8 · Special theory of relativity: Michelson-Morley experiment and Einstein’s postulatesWrite short notes on any TWO of the following. (10 each) (20) a. Kepler’s Law of Periods b. Michelson interferometer c. Young’s double slit experiment
3. Q4 · equivalence of mass and energy(a) What was Physics like before relativity and how did Einstein come up with his (10) theory? Mathematically explain how mass and energy is interchangeable? (b) Discuss in detail the relativity of length using Einstein’s special theory of (06) relativity. (c) Calculate the mass equivalent of energy from an antenna radiating 10KW for 24 (04) (20) hours.
4. Q6 · Waves and Oscillations, Optics(a) For a wave travelling through a medium, demonstrate that the total energy per (10) unit volume is always equal to one half the kinetic and one half the potential energy. (b) The longitudinal waves can pass through solids. How it is possible and on what (06) parameters the velocity of such waves will depend? (c) The angular Vibrational frequency of CO molecule is 0.6x1015s-1. Calculate the (04) (20) amount of work required for stretching it by 0.5Å from the equilibrium position.
5. Q3 · Heat and Thermodynamics(a) Explain the rotational kinetic energy and determine its formula for a disc, hoop (10) and sphere. (b) What do you mean by the term ‘inertia’ in physics? Calculate respectively the (06) rotational inertia of a solid cylinder and a hollow cylinder about an axis of symmetry. (c) Calculate the angular speed of the second’s hand, minutes hand and hour’s hand (04) (20) of a watch.
6. Q7 · temperature(a) An ideal gas is enclosed in a cylinder with movable piston. Calculate the work (10) done on such gas and show that pressure force is non-conservative. (06) (b) State and briefly explain the intermolecular forces. (c) Oxygen gas having a volume of 1130cm3 at 42°C and a pressure of 101kPa (04) (20) expanded until its volume is 1530cm3 and its pressure is 106kPa. Find the number of moles of oxygen in the system and its final temperature.
7. Q3 · Electricity and Magnetism(a) Consider a pair of copper wires 1 mm in diameter and 5 cm apart. In copper the (8) number of conduction electrons per cubic meter is 8.45 x1028. Suppose their mean drift velocity v is 0.3 cm / s, calculate current in each wire. (b) If the wires are 20 cm apart, calculate the magnetic force on the wires. (8) (c) Define electric current in a wire with respect to number of charges and their drift (4) (20) velocity.
8. Q4 · Electricity and MagnetismGive expressions for the following quantities in terms of e, h, c, k, m e and m p . (a) The energy needed to ionize a hydrogen atom. (5) (b) The difference in frequency of the Lyman alpha line in hydrogen and deuterium (5) atoms. (c) The magnetic moment of the electron. (5) (d) The spread in measurement of the π0 mass, given that the π0 lifetime is τ. (5) (20)
9. Q8 · Maxwell's equations in integral and differential formWrite Notes on any TWO of the following: (10 each) (20) (a) Maxwell’s Equations (b) Magnetic Materials: (Ferro-Dia-Para) (c) Black Body Radiation
10. Q2 · time dependent and independent Schrodinger equationA particle of mass m is in the state mx 2 −a[� �+it] ψ(x, t) = A e h Where A and a are positive constants. (a) Find A. (5) (b) For what potential energy function V(x) does ψ(x, t) satisfy the Schrodinger (5) equation? (c) Calculate the expectation values of x, x2, p, and p2 (5) (d) Find σ x and σ y . Is their product consistent with the uncertainty principle? (5) (20)
11. Q5 · angular momentum(a) An atom is capable of existing in two states: a ground state of mass M and an (7) excited state of mass M + ∆. If the transition from ground to excited state proceeds by the absorption of a photon, what must be the photon frequency in the laboratory where the atom is initially at rest? (b) Derive the energy levels of the hydrogen atom, from Coulomb’s law and the (7) simple quantization of angular momentum. (c) In radio astronomy, hydrogen atoms are observed in which, for example, radiative (6) (20) transitions from n = 109 to n = 108 occur. What are the frequency and wavelength of the radiation emitted in this transition?
12. Q6 · Solid State Physics(a) Consider the elastic vibrations of a crystal with one atom in the primitive cell and (12) calculate the frequency of an elastic wave in terms of the wavevector that describes the wave and in terms of the elastic constants. (b) Describe vibrations of crystal. (8) (20)

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