Anna University Coimbatore 2009 B.E Engineering Physics Ph 080040002--ii - Question Paper

ANNA UNIVERSITY COIMBATORE
B.E/B.TECH DEGREE EXAMINATION, OCTOBER 2009
SECOND SEMESTER
PH 080040002-ENGINEERING PHYSICS-II
(REGULATION 2008)




PART A (10X2=20 MARKS)


1. On the basis of free electron motion in a conducting material discuss the resistance to a flow current.

2. obtain the drift velocity of free electrons with mobility of 3.5 x 10^-3 m^2/Vs in cu for an electric field of 0.5 V/m

3. elaborate the main drawbacks of classical free electron theory?.

4. describe the Fermi energy of metals?

5. What is covalent bond? provide the structure of a crystal having this bond

6.find the resistance of an intrinsic ge rod of one cm long, 1mm wide and 1mm thick at 300k.the intrinsic carrier density is 2.5 x 10^19/m^3 at 300k and the mobilities of electron and hole are 0.39 and 0.19 m^2 V^-1 s^-1.

7. What is effective mass of an electron?

8. Mention any 2 applications of Hall Effect experiments in semiconductors

9. describe energy product of a magnetic material.


10. How will you differentiate magnetic materials based on their spin alignment?


11.Calculate the critical current for a wire of lead with diameter one mm at 4.2 k critical temperature for lead is 7.18 k and Ho=6.5 x 10^4 A/m.

12. elaborate high temperature semiconductors? provide the examples.

13. describe polarizablity of a dielectric. provide the expression for orientation polarization.

14. Write a note on temperature dependence of polarization.

15. compute the electronic polarizablity of xenon. the radius of xenon atom is 0.158 nm.

16. describe dielectric loss.

17. elaborate metallic glasses?

18. Mention few the properties of Ni-Ti alloy?

19. List the synthesis methods of nano manterials.

20. provide the applications of carbon nano tubes?




PART B- (5 X 16=80)


21. i. elaborate the postulates of classical free electron theory?
ii.Derive an expression connecting electrical conductivity and relaxation time..

22. i.What is density of states? Derive an expression for density of states using that
ii.Obtain an expression for Fermi energy of a metal at 0k..
discuss wiedemann-franz legal regulations..

23. i.Derive expression for carrier concentration and Fermi energy in a
N-type semiconductor.
ii.Explain the variation of Fermi level with temperature and donor impurity
concentration.

24. i.Give the theory of Hall Effect.
ii.Using Hall Effect how will you determine the electrical conductivity of a
semiconductor?

25. i.What are reversible and irreversible domains? Based on that discuss the
phenomenon of hysteresis in ferromagnetic materials
ii.Explain magnetic recording and readout of data n floppy disc.

26. i.What are super conductors? provide 2 examples. discuss their properties..
ii.Discuss the application cryotron.

27. i.Explain the term internal field in solids. Derive and expression for the lorentz field
for elemental dielectrics.
ii.Obtain clausius-mossotti formula for elemental solid dielectrics.



28.i.Discuss the characteristics of shape memory alloys and their applications.
ii.Describe a method for the fabrication of carbon nano-tubes.

Earning:   Approval pending.