UPSC Physics Optional PYQs (CSE & IFoS)PYQs

Write a short note on Rutherford scattering.

Write a short note on Lorentz transformation.

Explain what you mean by processional torque. Deduce an expression for the time period of processional motion of gyroscope in terms of relevant quantities.

If the earth were to rotate at n times its present speed of rotation about its axis, the apparent weight of a body at the equator would assume zero value. Find an expression for n.

Explain what is meant by Coriolis force. Discuss the action of Coriolis force on a body failing freely on the earth at altitude \lambda.

State and explain variation mass with velocity, hence find an expression for the density of a body in an arbitrary inertial frame of reference.

What is centre of mass? Show that there exists only one centre of mass in system of particles. Discuss the usefulness of centre of mass in studying motion of system of particles.

Describe and explain the theory and operation of the Zener diode. Explain what is meant by (i) Avalanche breakdown (ii) Zener breakdown

Show that in the non-degenerate approximation the Fermi level in an n-type semiconductor is slightly below the bottom of the conduction band and in p-type it is slightly above the top of the valence band, but in both cases it remains within the band gap.

Explain ferrimagnetism. How is it different from antiferromagnetism?

Describe the characteristics of grounded emitter transistor amplifier circuit and determine expression for (i) Input resistance (ii) Output resistance (iii) Current gain (iv) Voltage gain (v) Power gain

What are weak interactions? Mention the various processes in which the weak interactions play a dominant role.

Describe in brief a linear accelerator. How are the lengths of linear accelerator tubes calculated? Name some particles for which this technique is applied and order of energies reached.

Write an essay on elementary particles with the following points: (i) Types of particles (ii) Quantum numbers (iii) Conservation laws (iv) Types of interactions

Give the salient features of electronic band spectra of diatomic molecules in emission. Why would absorption, spectra of the same molecules be simpler? The absorption spectrum of iodine (\text{I}_2) vapour has longest wavelength band at \lambda_0, initial band separation \Delta\lambda_0, and bands converge at wavelength \lambda_0'. Relate these data broadly to the concerned parameters of \text{I}_2 molecule.

A sample shows a Raman line at 4200\text{ \AA}, with incident radiation having \lambda = 4400\text{ \AA}. Where Will the other corresponding Ramas line fall with the same exciting radiation? Will that line be stronger or weaker than the line at 4200\text{ \AA}, and why?

With incident X-rays of wavelength 1.618\text{ \AA} Compton scattering is observed at 90^\circ from the incident beam. Calculate. (i) the wavelength of Compton radiation, and (ii) the angle at which the recoil electron may be observed. In what state should the electrons be in Compton scattering?

Using de Broglie's relation, deduce an expression for energy values of a particle enclosed in a one-dimensional box. 'Free electrons' in a long-chain molecule may be treated as particles in a one-dimensional box. From a long-chain molecule of length 60\text{ \AA} deduce the lowest three energy state values in eV units.

What values of J quantum number may be observed in normal atoms of alkalis and alkaline earths ? Which of the spectral lines in alkaline earth would show normal Zeeman effect and why?

Define thermodynamic temperature of a magnetic system. Making use of Gibb's equation, derive an expression for cooling produced due to adiabatic demagnetization process. Why is the method use only after pre-cooling to a low temperature?