### Ph23 - ENGINEERING PHYSICS-II B.E/B.TECH DEGREE EXAMINATION, APRIL/MAY 2009 ANNA UNIVERSITY TIRUNELVELI

ANNA UNIVERSITY TIRUNELVELI
B.E/B.TECH DEGREE EXAMINATION, APRIL/MAY 2009
SECOND SEMESTER
Ph23 - ENGINEERING PHYSICS-II
(REGULATION 2008)
PART A (10X2=20 MARKS)

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 0k?
3. the resistivity of intrinsic semiconductor germanium at 300k is 0.47 ohm .m. if the electron and hole mobilities are 0.38 and 0.18 m^2 V^-1s^-1.calcualte the intrinsic carrier density at 300k.
4. Define hall effect?.
5. What is Bohr magneton?
6. Superconductors tin has a critical temperature of 3.7k at zero magnetic field and a critical field of 0.0306T at 0k.find the critical magnetic field at 2k.
7. How temperatures effect the polarization of dielectrics?
8. Give any two applications of ferroelectric materials.
9. Name any two examples of ferroelectric materials.
10. What are carbon nano tubes?

PART B- (5 X 16=80)

11.i. starting with the classical free electron theory of metals obtain an expression for electrical and thermal conductivity and hence prove wiedemann – franz law..
Or
12
i. Define Fermi energy.
ii. Starting with the density of energy of energy states obtain an expression for Fermi energy of the electron at absolute 0k..
iii. Obtain an expression for average energy of an electron at T=0k.
13.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
14.i. obtain an expression for hall coefficient
ii. How will you measure hall coefficient experimentally?
iii. Describe any two applications of hall effect..
15.i. describe the Ferro magnetic domain theory in detail and how will you account hysteresis of Ferro magnetic material based on domain theory.
Or
16.i. Discuss the type I and type ii super conductors.
ii. Describe the BCS theory of super conductivity.
17.i. Describe the different types of polarization.
ii. Obtain an expression for electric and ionic polarization in dielectrics.
Or
18.I. Starting with the internal field in a dielectric. Obtain clausius-mossotti equation.
ii. Discuss the effect of frequency on polarization.
19. Write short note on:
i. Metallic glasses?
ii. Shape memory alloys.
Or
20.i. What are nano materials? Describe any two methods of production of nano materials. Discuss the application of nano materials.
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