B.Tech-COMMON PAPER 2nd Sem ENGINEERING PHYSICS(Anna University Trichy, Tiruchi, Tamil Nadu-2009)
Thursday, 23 September 2010 05:34Abhigyan Singh
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PART B-(5 X 16=80 Marks)11.
- Derive an expression for the electrical conductivity of metal.
- The density and atomic weight of copper are 8900 kgm^-3 and 63.5.the relaxation time of electron in Cu at 300k is 10^-14s.assuming that each copper atom contributes one free electron, calculate the electrical conductivity of copper.
Or
12
- Define density of states.
- Derive an expression for the density of states in a metal.
- A conducting rod contains 8.5 x 10^28 electrons
Or
13. What is Hall Effect? per cubic meter. Calculate the electrical conductivity and mobility of electrons, if the collision time for scattering is 2 x 10^-14 sec.
14.
- Derive an expression for the concentration of electrons in the conduction band of an intrinsic semiconductor.
- With necessary theory, describe the method of determining the band gap of an intrinsic semiconductor.
15.
- Give the theory of Hall Effect.
- The density of silver is 10.5 x 10^3 kg/m^3.the atomic weight of silver is 107.9.Assume that each silver atom provides one conduction electron. the electrical conductivity of silver at 20c us 6.8 x 10^7 ohm^-1m^-1.determine the carrier concentration and mobility of electrons, if N=6.02 x 10^26 atom/k. mol.
16.
- Give the Weiss theory of ferromagnetism and derive an expression for its susceptibility.
- Describe the structure, properties and applications of ferrites.
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17.
- Distinguish between soft and hard magnetic materials.
- Explain Meissner effect.
- Describe type I and type ii superconductors.
18.
- Define local field in a dielectric.
- Derive an expression for the local field in a dielectric for a cubic structure.
- Deduce Clasius - mosatti relation.
Or
19.
- Discuss in detail the different dielectric breakdown mechanisms.
- Describe the frequency dependence of polarization of a dielectric material.
20.
- What are metallic glasses? how are they prepared?
- Describe their properties and application.
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20.
- What are nano-phase materials?
- Describe the method of producing nano materials using
- Chemical vapour deposition method
- Plasma assisted deposition method.
- Write a short note on carbon nano tubes.
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