PHYSICS MAGADH UNIVERSITY QUESTION POST- GRADUATE

PHYSICS MAGADH UNIVERSITY QUESTION POST- GRADUATE

                                                                       2015-2017
                                                                      Time: 3 hours
                                                                     Full Marks: 80
                                             Candidates are required to give their answers in
                                                 their own words as far as practicable.
                                                   The questions are of equal value.
                                                     Answer five questions including
                                                      Q. No. 1 which is compulsory.

1. Answer any four questions:
    (a). Explain Hall effect
    (b). Explain Nearly free electron approximation.
    (c). What are magnons?
    (d). Outline the effects which destroy superconductivity.
    (e). Explain Bose- Einstein condensation.
    (f) . What is Zero sound?
    (g). What is Kondo effect?
    (h). Explain two- fluid theory of super fluid.

2. Give the fight binding approximation of electron in a crystal. Show how it leads to the formation of energy bands in solid.

3. Distinguish between the metal, insulator and semiconductor on the basis of band theory of solid.

4. What is Ferromagnetism? Discuss the quantum theory of ferromagnetism.

5. Give an account of Neel's theory of antiferromagnetism. Show how the ferromagnetic behaviour of ferrits can be explained from Neel's theory.

6. What is Superconductivity? Explain Meissner effect. What are the possible application of superconductor?

7. Discuss BCS theory of superconductivity and obtain and expression for transition temperature Tc and energy gap parameter D (o).

8. Discuss the propagation of different types of sound wave in liquid He II.

9. Discuss Bogoliubov pairing theory of liquid He(4) (here 4 is the atomic mass of helium). what are the drawbacks of Pairing theory?

10. Write short notes of any two of the following:
      (a). Megnetoresistance effects
      (b). Block theorem
      (c). Charge density waves
      (d). Spin glass

      (e). Landau theory of Fermi liquid