LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

THIRD SEMESTER – NOVEMBER 2010

    PH 3810  – SOLID STATE PHYSICS – I

 

 

 

Date : 29-10-10                 Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

SECTION – A

Answer all the questions.                                                                                10 x 2 = 20

1. Determine the Miller indices of a plane that makes intercepts of 3Å, 4Å and 5Å of an orthorhombic crystal with a:b:c = 1:2:5
2. Mention the various types of one and two dimensional defects.
3. The unit cell parameter of NaCl crystal is 5.6Å and the modulus of elasticity along [100] direction is 5 x 10¹⁰ Nm^-2. Estimate the wavelength at which electromagnetic radiation is strongly reflected by the crystal. Given At.Wt of Na = 23 and of Cl =37.
4. Distinguish between normal and Umklapp process.
5. The density of Zn is 7.13 x 10³ Kgm^-3 and its atomic weight is 65.4. Calculate the Fermi energy for Zinc. Also calculate the mean energy at 0 K.
6. State Widemann-Franz law.
7. State Bloch’s theorem.
8. Distinguish between reduced zone and extended zone scheme.
9. Discuss any two characteristic properties of Fermi surface.
10. Mention any two effects of electric field on the Fermi surface.

 

SECTION –B

Answer any four questions.                                                                          4 x 7.5 = 30

11. Obtain the reciprocal lattice vectors for a bcc lattice and find the number of nearest neighbours and their coordinates.
12. Derive an expression for the thermal expansion coefficient including the anharmonic contribution to lattice vibrations.
13. Explain with necessary theory, the Hall effect.
14. Discuss the effective mass concept and account for the negative effective mass.
15. Explain the concepts of electron, hole and open orbits in the construction of 2D Fermi surface.

 

SECTION -C

Answer any four questions.                                                                           4 x 12.5 = 50

16. (a) Derive the Bragg’s equation as a special case of the Laue equations.

(b) Describe the construction of Ewald’s sphere and express Bragg’s diffraction condition in the vector form.

17. Discuss the dynamics of a one dimensional diatomic lattice. Distinguish between optic modes and acoustic modes.
18. Obtain an expression for the electronic heat capacity.
19. With necessary theory obtain the energy band structure using the Kronig-Penny Model and explain the origin of band gap.
20. Establish the quantisation of electron orbits in an external magnetic field and derive an expression for the cyclotron frequency.

 

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