Anna university - Tirunelveli
April/May 2009
Second semester
Engineering physics II
Part-A
1. State widemann – franz law.
2. The fermi energy of silver is 5.51 eV . What is the average energy of a free electron at 0 K.
3. The resistivity of intrinsic semiconductor germanium at 300 k is 0.47 Ω.m. If the electron and hole mobility are 0.38 and 0.18m2.v-1s-1 calculate the intrinsic carrier density at 300 k.
4. Define hall effect.
5. What is bohr magneton?
6. Superconductors tin has critical temperature of 3.7 k at zero magnetic field and a critical field of 0.0306t at 0k. Find the critical magnetic field at 2 k.
7. How temperature effect the polarization of dielectrics?
8. Give any two applications of ferroelectric materials.
9. Name any two examples for metallic glasses.
10. What are carbon nanotubes?
Part-B
11. (a) Starting with the classical free electron theory of metals obtain an expression for electrical and thermal conductivity and hence prove widemann – franz law.
(Or)
(b) (i) Define fermi energy.
(ii) Starting with the density of energy states obtain an expression for fermi energy of the electron at absolute zero.
(iii) Obtain an expression for average energy of an electron at t=0k.
12. (a) (i) obtain an expression for intrinsic carrier concentration in an intrinsic semiconductor.
(ii) How will you determine the energy gap of an intrinsic semiconductor.
(or)
(b) (i) Obtain an expression for hall coefficient.
(ii) How will you measure hall coefficient experimentally?
(iii) Describe any two applications of hall effect.
13. (a) Describe the ferro magnetic domain theory in detail and how will you account hysteresis of ferro magnetic material based on domain theory.
(or)
(b) (i) Discuss the type I and type II super conductors.
(ii) Describe the BCS theory of super conductivity.
14. (a) (i) Describe the different type of polarization.
(ii) Obtain an expression for electronic and ionic polarization in dielectrics.
(or)
(b) (i) Starting with the internal field in a dielectric obtain clausius-mossotti equation.
(ii) Discuss the effect of frequency polarization.
15. (a) Write a note on:
(i) Metallic glasses
(ii) Shape memory alloys
(or)
(b) What are nanomaterials? Describe any two methods of production of nanomaterials. Discuss the applications of nano materials.