LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
M.Sc. DEGREE EXAMINATION – PHYSICS
THIRD SEMESTER – NOVEMBER 2003
PH 3801 / PH 921 – SOLID STATE PHYSICS
05-11-2003 Max. : 100 Marks
1.00 – 4.00
PART – A
Answer ALL question. (10 x 2 = 20)
- Define the reciprocal lattice vector .
- What is a Van der Waal’s interaction?
- Outline the principles involved in the inelastic scattering of neutrons by PHONONS.
- State the implications of observing harmonic lattice vibrations.
- What is size effect?
- State Mathiessen rule
- What is a Fermi sphere?
- Distinguish between metals and insulators on the basis of energy bands and the number of electrons per primitive cell.
- State the difference in the paramagnetic behaviour of rare earth and iron group salts.
- State Curie-Weiss law and its significance.
PART – B
Answer any FOUR questions only (4 x 7.5 = 30)
- Obtain the dispersion relation for the one dimensional monoatomic lattice and PLOT w .
- Discuss how the nearly FREE electron model for a monoatomic lattice of lattice constant ‘a’ establishes origin of energy gap.
- What are the three different zone schemes for studying Fermi surface? Explain.
- Describe the three phonon collision process and briefly EXPLAIN its role in causing thermal resistivity.
- What are Magnons? Show that the fractional change of magnetization is proportional to T3/2.
-2-
PART – C
Answer any FOUR questions only. (4 x 12.5 = 50)
- Obtain the wave equation for an electron in a periodic potential of lattice constant ‘a’. Hence give the proof of Bloch theorem.
- a) Derive a quantitative expression for the electronic heat capacity of a free electron gas at low temperatures. (8.5)
- b) Quantitatively account for the electrical conductivity as a motion of the Fermi sphere. (4)
- a) Apply quantum theory to obtain Curie’s law of para magnetism. (8)
- b) Describe briefly de Haas Van Alphen effect. (4.5)
- a) Explain Ferromagnetic domains. (5)
- b) Establish theoretically the existence of Bloch Wall between domains in a ferromagnet. (7.5)
- Write short notes on any TWO of the following
- DEBYE’S T3-law.
- Isoentropic cooling by demagnetization
- Paulis Spin paramagnetism
Latest Govt Job & Exam Updates: