Dr MGR Educational and Research Institute 2009 B.E Information Science and Engineering Model -2 %28EEE%29 %2C PH 231 Materials Science - Question Paper

ans ALL ques. MAXIMUMUM MARKS 100
Part-a 10*2=20

1. elaborate Bravais lattices?

2. X-ray of wavelength 1.2 Angstrom are diffracted by (110) planes in a crystal at an angle 30 degree in the 1st order. compute the inter atomic spacing.

3. describe Fermi level.

4. compute the energy difference ranging from the least energy level and next possible higher energy level of an electron confined in a box of size one nm.

5. With increase of temperature the conductivity of semiconductor increases while that of matter reduces. provide reasons.

6. discuss the concept of hole in semiconductor.

7. What is bohr magneto?

8. elaborate various dielectric breakdown mechanisms.

9. Distinguish fluorescence and phosphorescence.

10. compute the wavelength of radiation emitted by an LED made up of a semiconductor material with band gap energy 2.8 eV.


Part-b 16*5=80

11(a) elaborate miller indices? Derive an expression for the interplanar spacing for (hkl) planes of a cubic structure.

(b) for a NaCl crystal, 1st order reflection maxima occurs at 5.9 degree. 8.4 degree and 5.2 degree for (100), (110) and (111) planes respectively. Prove that NaCl belongs to FCC structure.
12(a) Derive an expression for the density of states and based on that compute the carrier concentration in metals.

(Or)

(b) discuss superconducting phenomena. elaborate its properties ? Distinguish kind type one and kind two super conductors.
13(a) discuss the mechanism of intrinsic conduction in semiconductors. Derive an expression for conductivity of an intrinsic semiconductor in terms of carrier concentration and carrier mobility.

(Or)

(b) What is Hall coefficient ? Derive an expression for Hall coefficient. define an experimental setup for the measurement of the identical.

14(a) provide an account of Weiss theory of ferromagnetism and show from the plot of Langevin function, spontaneous magnetization exists ranging from the curie temperature and vanishes above the Curie temperature.

(Or)

(b) What is meant by local field in dielectric and how is it computed for a cubic structure? Deduce the Claussic-Mosotti relation.

15. Write an essay on thermography. What is its application?

Earning:   Approval pending.