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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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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

THIRD SEMESTER – APRIL 2012

PH 3810 / 3807 – SOLID STATE PHYSICS – I

 

 

Date : 21-04-2012             Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART – A

Answer ALL the questions:                                                                                                 (10 X 2 = 20)

1. List all the two dimensional lattices and the corresponding lattice specifications
2. Find the Miller indices for a plane with intercepts a/2,b,∞
3. How do you account for thermal expansion of solids?
4. State Widemann-Franz law.
5. State the assumptions of free electron theory of metals.
6. Plot phonon dispersion curve for a diatomic lattice.
7. Give the significance of effective mass of an electron.
8. What is forbidden energy gap?
9. Explain the concept of hole. Which has greater mobility, electron or hole?
10. Explain “quantization of electron orbits”.

PART – B

Answer any FOUR questions:                                                                                             (4 X 7.5 =30)

11. What is a reciprocal lattice? Obtain the primitive translation reciprocal lattice vectors for an FCC direct lattice.
12. Derive an expression for the thermal conductivity of a solid in terms of specific heat capacity.
13. Explain Hall effect based on the free electron theory of metals.
14. Discuss the different zone schemes by plotting suitable E-K curves.
15. Explain in detail the effect of electric field on the Fermi surface.

PART – C

Answer any FOUR questions:                                                                                             (4 X 12.5 =50)

16. i) Discuss the formation of diffraction pattern on the photographic film with the necessary theory of X- ray powder diffraction. (8.5)
17. ii) Write a short note on point defects.                                                    (4)
18. Derive an expression for the specific heat of solids on the basis of Debye model.
19. Obtain an expression for the density of states as a function of energy for electron gas in 3D at 0K. Hence derive expressions for Fermi energy and total energy.
20. Outline the theory of the Kronig-Penny model and hence discuss the formation of allowed and forbidden energy bands.
21. Describe any one experimental method of determining the Fermi surface.

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

THIRD SEMESTER – NOVEMBER 2012

PH 3810 – SOLID STATE PHYSICS – I

 

 

Date : 01/11/2012            Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

PART – A

Answer ALL questions:                                                                                                         (10×2=20)

1. In a cubic unit cell, find the angle between normals to the planes (111) and (121)
2. What is the difference between neutron diffraction and electron diffraction?
3. Define density of phonon state.
4. List the major contributions to the specific heat capacity.
5. What do you understand by free electron gas.
6. Write down the expression for the electronic contribution to specific heat capacity.
7. Why a solid whose energy bands are filled cannot be a metal?
8. Explain the concept of forbidden bands.
9. Define Fermi surface.
10. Explain electron and hole orbits.

PART – B

Answer any FOUR questions:                                                                                               (4×7.5=30)

11. Derive Laue’s equations for diffraction of X-rays in a crystal lattice.
12. Derive the w-k dispersion relationship for a one dimensional monoatomic lattice
13. Write a note on Fermi-Dirac statistics and explain the effect of temperature on Fermi-Dirac statistics
14. State and prove Bloch’s theorem.
15. Discuss any one experimental method of Fermi surface study.

PART – C

Answer any FOUR questions            :                                                                                             (4×12.5=50)

16. Discuss in detail with diagram Laue and powder method of determining crystal structure
17. Discuss the Debye model of lattice specific heat capacity. Explain how this model is able to account for low temperature and high temperature behaviour.
18. Explain the concept of density of available electron states in three dimensions. Obtain the expressions for the E_f0 and average kinetic energy.
19. Explain how the formation of bands in the Kronig-Penny model may be accounted for.
20. Discuss the theory of effect of electric field on the Fermi surface.

 

 

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