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Posted By: tasneem Member Level: Gold Posted Date: 27 Jun 2008
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2007 Anna University B.E PH-203 ENGINEERING PHYSICS II Question paper
B.E/B.Tech DEGREE EXAMINATION, MAY/JUNE 2008
Second Semester
PH-203-ENGINEERING PHYSICS -II
(Common to all branches)
Time: Three hours Maximum: 100 marks
Answer ALL questions
PART A –(10*2=20marks)
1.Calculate the electrical resistivity of sodium at 0° c .It has 25.33*10^27 electrons per unit volume and has a mean free time of 3.1*10^-14 S .
2.The occupied level of the electrons at 989 °c is above 0.5ev of the Fermi level of a material. What is the probability of occupation of electrons at this temperature?
3.If the mobilities of electron and holes in an intrinsic semi conductor at 300°K are 0.36 and 0.14 m²/v/s.Calculate the number of charge carriers (given, the conductivity is 2.2/ohm-m).
4.If the slope of the graph between ln s and 1/T is 3.75*10³, find the band gap of the semiconductor.
5.What are soft and hard magnetic materials? List any two applications.
6.What are ferrites?Give their structural formula.
7. What are the dependencies in electronic and ionic polarisations?
8.If the relative susceptibility of a material is 4.94 and the number of dipoles per unit volume is 1000,calculate the polarisability of the material .
9.Calculate the critical magnetic field of a super conducting material at 2°K,
if its Tc = 3.7 ° K and the critical magnetic field at 0°K is 0.0306 Tesla.
10. Describe Superconducting Quantum Exchange Devices (SQUIDS)
PART B ---(5*16=80 marks)
11. (a)(i) Derive an expression for the electrical conductivity based on free
electron theory. [Marks 12]
(ii) List the drawbacks of free electron theory. [Marks 4 ]
Or
(b) Derive an equation for electron concentration in any conductor using
Fermi distribution function. Use it to express the Fermi energy of
electrons at absolute zero. [Marks 16]
12.(a)(i) Derive an expression for carrier concentration in P-type
semiconductors. [Marks 10]
(ii) Discuss the variations of the Fermi level with temperature in N and P
type semiconductors. [Marks 6]
Or
(b) What is Hall effect? Derive an equation for Hall coefficient and explain
an experiment to determine it. What is the interence one can get out
of it? [Marks 16]
13.(a)(i) Explain the hystersis behaviour of ferromagnetic materials using
domain theory. [Marks 12]
(ii) Distinguish dia, para and ferro magneticmaterials. [Marks 4]
Or
(b)(i) List the conditions for magnetic parameters for recording
applications. [Marks 4]
(ii) Write notes on magnetic recording systems. [Marks 12]
14. (a) What do you mean by Lorentz field in dielectrics? Derive an
expression for the same and use it to arrive at Clausius-Mosotti
equation and give its significance. [Marks 16]
Or
(b)(i) Explain dielectric loss and its measurability. [Marks 6]
(ii) What is dielectric breakdown? Explain in detail the mechanisms
involved in it. [Marks 2+8]
15. (a)(i) Explain Meissner effect and isotope effect in super conductors.
[Marks 6]
(ii) How will you classify superconductors and explain in detail.
[Marks 6]
(iii) What are High Tc super conductors? [Marks 4]
Or
(b)(i) What are metallic glasses? Why they are called so? [Marks 2]
(ii) Explain the properties of metallic glasses and give their applications.
[Marks 6]
(iii) How do nanomaterials different from bulk? Explain the preparation
by any one method and give their properties. [Marks 2+6]
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