LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – PHYSICS
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SIXTH SEMESTER – April 2009
PH 6606 – SOLID STATE PHYSICS
Date & Time: 21/04/2009 / 9:00 – 12:00 Dept. No. Max. : 100 Marks
PART A
Answer all questions. All questions carry equal marks. (10 x 2 = 20 marks)
- Define coordination number.
- The lattice constant of a Cubic lattice is a, Calculate spacing between (0, 1, 1) and
(1, 1, 2) planes.
- Write Laue equations.
- The Bragg’s angle for (2, 2, 0) reflection from Nickel(f c c) is 45˚. when X-rays of
wavelength 1.75Å are employed in a diffraction experiment,. What is the lattice constant?
- Mention any two assumptions of classical theory of specific heat of solids.
- State Gruneisen’s law.
- What is Hall effect?
- What do you understand by density of states?
- Distinguish between type I and type II semiconductors.
- What is Meissner effect?
PART B
Answer any four questions. (4 x 7.5 = 30 marks)
- What are Miller indices? How are they determined?
- Write note is on Neutron diffraction.
- Debye temperature of carbon(diamond)structure is 1850K. Calculate the molar specific heat
for diamond at 20K. Also compute the highest lattice frequency involved in the Debye
theory.
- Calculate the number of energy states available for the electrons in a cubical box of side 1 cm
lying below an energy of 1 electron volt.
- Explain I-V characteristics of d.c Josephson effect.
PART C
Answer any four questions. (4 x 12.5 = 50 marks)
- Classify the seven systems crystal on the basis of 14 bravais lattices. Explain with the help of
the unit cell lattice parameters and giving examples.
- With a neat diagram explain the powder method for determining the structure of a crystal.
- Work out an expression for the specific heat of solids following Einstein model. Mention its
draw backs.
- a) Derive an expression for the Fermi energy of a free electron gas in three dimensions. (8)
- b) Estimate the lattice specific heat of sodium (at constant volume) at 20K. The Fermi
temperature of sodium is 3.8 x 104 K and its Debye temperature is 150 K. (4.5)
(K = 1.38 x 10-23 J/K)
- Outline qualitatively the BCS theory of superconductivity.
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