B.Tech-COMMON PAPER 2nd Sem ENGINEERING PHYSICS(Anna University Trichy, Tiruchi, Tamil Nadu-2009)

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.

Or

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.

Or

20.

• What are nano-phase materials?
• Describe the method of producing nano materials using

1.                 Chemical vapour deposition method
2.                  Plasma assisted deposition method.

• Write a short note on carbon nano tubes.

Earning:  ₹ 4.00/-