Aligarh Muslim University (AMU) 2011 B.Sc Physics Atomic, Molecular, Laser and CondMatter - Question Paper

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2010-2011 B.Sc. (HONS.) (PART - m) EXAMINATIONS (PHYSICS)

ATOMIC, MOLECULAR, LASER AND COND. MATTER PHYSICS

(PH-315)

Maximum Marks : 40    Duration : Three Hours

Note: (i) Answer all questions.

(ii) Use of Calculator is allowed.

1 .(a) Describe the fine structure of hydrogen atom and explain the Lamb shift observed in [4] this spectrum.

(b) What is the effect of Paulis exclusion principle on the term system? Obtain the [3] levels of d² configuration using Briet scheme of magnetic quantum numbers.

OR

(b') Illustrate the origin of sodium Di and D2 lines and explain their behaviour in the [3] presence of magnetic field.

2.(a)    Describe Raman scattering on the basis of classical theory. Explain pure rotational [5] Raman spectrum of diatomic molecule.

(b) Applying Linear Combination of Atomic Orbital (LCAO) approximation, describe [2] the formation of bonding and anti-bo Jiding of hydrogen.

OR

2'.(a) Describe the rotational spectrum of non-rigid molecule and explain the selection [4] rules associated with it. Compare the observed spectrum with the spectrum of a rigid rotator.

(b) "Describe the intensity of vibrational-electronic spectra on the basis of Frank-Condon [3] principle.    ; \

3.<ji)    Explain the terms: (i) population inversion, (ii) Optical pumping (iii) spontaneous    [3] and stimulated emission.

(b ith suitable diagram, explain the construction and working principle of N2 laser.    [3] What is super-radiance?

4.(a)    Describe different lattice types in three dimension.    [3]

(b)    Find the expression for Madelung energy of an ionic crystal.    [2]

(c)    Aluminium has an fee structure. Its density is 3 x 10³ kg/m³. Calculate the unit cell [2] dimension and the atomic diameter. The atomic weight of aluminium is 27.0.

5.(a) Discuss Laues interpretation of x-ray diffraction by crystals.    [3]

OR

Derive the dispersion relation for the vibration of dimensional monatomic lattice.    [3]

(b)    . Show that the unit cell volume in reciprocal lattice is inversely proportional to that in [2]

the direct lattice.

(c)    Why is the neutron diffraction used to study the structure of magnetic materials? _ [1]

-2-

6.(a) Write down the basic assumptions of Drude model. [2] (b) What is Fermion? Derive the expression for Fermi-Dirac distribution and show its [3] variation with temperature. (c) State the Bloch theorem. How is the free electron wave function modified in a [2] periodic potential?

OR

6\(a)	Derive the expression for dc electrical resistivity based on classical model. What is	[3]
	Mathiessens rule?
(b)	Describe the origin of energy gap in a crystal.	[2]
(c)	What is Meissner effect? Show that the Meissner effect is a necessary condition for a	[2]
	material to be superconductor.

Attachment: aligarh-muslim-university--amu--2011-b-sc-physics-275-1.pdf

Earning:   Approval pending.