Search, filter, and study UPSC Civil Services & IFoS Physics past year questions with rigorous derivations, formulas, and step-by-step solutions.
Buy PYQ Solution Manual →
Consider two electrons system in (3p)^1(4s)^1 configuration. Derive the allowed energy states of the system in (i) LS coupling and (ii) jj coupling sketching the energy level diagram in each case. Name the interactions which are responsible for different splittings.
What is the main inference drawn from the Stern Gerlach experiment ? What would be the change in the result in the following cases :
(i) electron spin is \frac{3}{2}\hbar instead of \frac{\hbar}{2}.
(ii) a beam of neutral atoms is passed through a homogeneous magnetic field.
Explain Stokes and anti-Stokes Raman scattering with the help of energy level diagram. For a diatomic molecule, obtain expressions for transition energies of its Raman spectra with rotational fine structure and hence the wave numbers of the Stokes lines.
Obtain the frequency $ u_r$ of the spectral line of rotation spectra of a diatomic molecule and discuss the characteristics of its spectrum.
Outline elementary theory of Nuclear Magnetic Resonance (NMR) and discuss its applications.
What is Raman effect? Describe briefly the chief characteristics of pure rotational spectra. The small rotational Raman displacement for HCl molecule is 41.6\ \mathrm{cm}^{-1}. Find the internuclear distance between the atoms forming the molecule.
Outline the Stern-Gerlach experiment and discuss its importance in the context of quantum nature of atom.
Consider a hydrogen atom in Bohr atomic model. Outline its importance in the context of spatial quantization and the spin of the electron.
What is Lamb shift? What is its significance in determining the fine structure of \mathrm{H}_{\alpha} Balmer line in hydrogen atom?
Explain in detail L-S coupling and j-j coupling schemes.
Compute the allowed spectral terms for two non-equivalent p-electrons on the basis of Pauli’s exclusion principle.
The series limit wavelength of Balmer series in hydrogen spectrum is experimentally found to be 3646\,\mathring{\mathrm{A}}. Find the wavelength of the first line of this series.
Describe Stern-Gerlach experiment. Discuss how it has explained space quantization and electron spin. Find the value of angle between the spin angular momentum \vec{S} and its z-component of an electron moving along the external magnetic field \vec{B}.
In the Stern-Gerlach experiment using Ag atoms, the oven temperature is 1000 K, l \approx 25\ \mathrm{cm} and \frac{\partial B_z}{\partial z} \simeq 10^{+3}\,\text{Tesla/m}. Calculate the separation of the two components.
Explain Russel Saunders coupling. Discuss the summation rules for orbital angular momentum, spin angular momentum and total angular momentum quantum numbers.
What is 'multiplicity' ? Give the term symbol for the following cases :
(i) S = \frac{1}{2} \qquad L = 2
(ii) S = 1 \qquad L = 1
State the postulates of Bohr regarding his atom model. Obtain the expressions for the radius and electron-energy of the n^\text{th} orbit. Explain how Bohr's atom model successfully accounts for the hydrogen spectrum.
Use Hund's rules to find the ground-state quantum numbers, L and S of (i) Carbon and (ii) Oxygen atoms.
Find the magnetic moment of an atom in {}^3P_2 state, assuming that LS coupling holds for this case.
Obtain Zeeman splitting for sodium D-lines.