UPSC Physics Optional PYQs (CSE & IFoS)PYQs

Explain why in optical absorption discrete lines are observed but X-ray absorption shows continue with edges. Why the emission and absorption spectra of X-rays are not identical ?

Write in brief the differences between the IR active and Raman active bands.

Explain the origin of continuous X-rays. Compare the phenomenon with photoelectric effect.

Draw the energy level diagram and show the allowed transitions for Zeeman pattern for n = 3_1 \rightarrow 2_0 transition line of a hydrogen atom placed in a uniform magnetic field of 1\text{ kg}. Calculate the doublet splittings.

Draw the expression for Lande's g-factor for LS coupled state.

Calculate the bond length and force constant of the bond of {}^{12}\text{C}\ {}^{16}\text{O} molecule; given 0 \rightarrow 1 rotational line in v = 0 state is at 115.3\text{ GHz} and the wavelength of the vibrational frequency is 14.7\ \mu\text{m}.

Write a short note on Stellar spectra.

Explain the fine structure of H_\alpha line of H-atom arising due to LS coupling.

Describe Frank Hertz experiment to establish the quantization of energy levels.

Explain the orgin of anti-Stokes lines in Raman spectra.

What is space quantisation? Discuss the Stern Gerlach experiment establishing the space quantisation.

What are the term symbols of 2 equivalent p electrons? Write down the term symbols in ascending order of energies.

Describe briefly how it is possible to determine the elements present at the surface of a given star.

Discuss the gross and fine structure of electronic band spectra of a diatomic molecule.

Give the theory of vibration-rotation spectra of diatomic molecules. Explain the nature of P, Q, R branches.

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?

Raman effect differs from Rayleigh scattering Explain. Explain qualitatively how Raman lines originate. What is the difference between Raman scattering and compton scattering?

Write a short note on Pauli's exclusion principle and its application.

Give the quantum numbers of the states whose energy difference accounts for the two D-lines of sodium. Find the energy difference for D_1 and D_2 lines in electron volts. (Wavelength separation = 6\text{\AA}, Mean wavelength = 5893\text{\AA})