PH 2161 ENGINEERING PHYSICS-II Question Bank - June 2010 Question Paper

Anna University
June 2010 Question Paper
Regulation 2008
PH 2161-ENGINEERING PHYSICS-II

PART A — (10 X 2 = 20 Marks)

1. Mention the demerits of classical free electron theory.
2. Calculate the Fermi energy of copper at 0k if the concentration of electron is 8.5x 10^28m^-3.
3. Distinguish between n-type and p-type.
4. Mention the uses of Hall Effect.
5. The transition temperature for superconducting material is 3.7 k at zero magnetic field and critical field is 0.0306 A/m at 0k.calculate the critical field at 2k.
6. Define anti ferromagnetism. Mention two materials that exhibit anti ferromagnetism.
7. What is ionic polarization? Write an expression for ionic Polarisability.
8. State the properties of ferroelectric materials.
9. Explain shape memory effect.
10. Name the types of metallic glasses and mention few metallic glasses.

PART B - (5 X 16=80 Marks) 

11.i. Define drift velocity and relaxation time.

ii. Derive an expression for both electrical conductivity and thermal conductivity of electrons in metal.

Or

12i. Define density of states. 

    ii. Derive an expression for the density of states in a metal.

  iii. A conducting rod contains 8.5 x 10^28 electrons per cubic meter. Calculate theelectrical conductivity and mobility of electrons, if the collision time for scattering is 2 x 10^-14 sec.

13.i. Derive an expression for the concentration of electrons in the conduction band of an intrinsic semiconductor. 

ii. With necessary theory, describe the method of determining the band gap of an intrinsic semiconductor. 

Or 

14.i. What is Hall Effect? ii. Give the theory of Hall Effect. 

iii. 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 electricalconductivity of silver at 20c us 6.8 x 10^7 ohm^-1m^-1. determine the carrierconcentration and mobility of electrons, if N=6.02 x 10^26 atom/k. mol.

15.i. Give the Weiss theory of ferromagnetism and derive an expression for its susceptibility.
ii. Describe the structure, properties and applications of ferrites.

Or

16.i. Distinguish between soft and hard magnetic materials.
ii. Explain meissner effect. iii. Describe type I and type ii superconductors.

17.i. Define local field in a dielectric.
ii. Derive an expression for the local field in a dielectric for a cubic structure.
iii. Deduce clarsirs-mosatti relation.

Or

18.i. Discuss in detail the different dielectric breakdown mechanisms.
ii. Describe the frequency dependence of polarization of a dielectric material.

19.i. What are metallic glasses? how are they prepared?
ii. Describe their properties and application.

Or

20.i. What are nano-phase materials?
 ii. Describe the method of producing nano materials using
a.Chemical vapour deposition method
b.Plasma assisted deposition method.
iii. Write a short note on carbon nano tubes.

Engineering Physics - II (HS1152) Model Question Papers - Important Questions

UNIT- I CONDUCTING MATERIALS

PART – A ( 2 Marks)

1. What are the postulates of free electron theory?
2. Define drift velocity and mean free path.
3. Define relaxation time and collision time.
4. Define electrical conductivity.
5. Define thermal conductivity.
6. State Wiedemann- Franz law. Give the value of Lorentz number.
7. What are the merits and demerits of free electron theory?
8. Define density of energy states in metal.
9. Define Fermi energy and give its importance.
10. Write down Fermi –Dirac distribution function.
11. Write down the difference between the quantum and classical free electron
theories?
12. Define carrier concentration of metals.
13. The Fermi temperature of a metal is 24600k.calculate the Fermi velocity.
14. Use Fermi function to obtain the value of f(E) for E-EF = 0.01eV at 200K
15. The thermal conductivity of copper at 20oC is 390 wm-1k-1 and 5.87x107 mho/m
respectively. Calculate the Lorentz Number.

PART – B ( 16 MARKS)

1.1 Deduce the mathematical expressions for electrical conductivity and thermal conductivity of a
material and hence obtain widemann - franz law. (6+8+2)
1.2 Derive an expression for the density of states and based on that calculate the carrier concentration in
metals .(12+4)
1.3 Write Fermi-Dirac distribution function. Explain how Fermi function varies with temperature.
Evaluate the Fermi function for energy KT above the fermi energy. (2 + 10 + 4)

UNIT-2 SEMI CONDUCTING MATERIALS

PART – A ( 2 Marks)

1. What are semi conductors?
2. What are called elemental and compound semi conductors?
3. What are the properties of semi conductor?
4. What are the differences between intrinsic and extrinsic semiconductors?
5. What do you mean by doping?
6. What is meant by band gap in semi conductor?
7. Compare p & n-type semiconductors.
8. What is donor and acceptor. Give examples for each?
09. Define Fermi level in case of semi conductors. Mention its position in intrinsic
and extrinsic semiconductors at 0k
10. What are the applications of Hall Effect?
11. The intrinsic carrier density is 1.5x1016/m3. if the electron and hole mobilities are
0.13 and 0.05 m2v-1s-1. Calculate its electrical conductivity?

PART – B ( 16 MARKS)

2.1 Derive an expression for the density of electrons and holes in an
intrinsic semi conductor (8+8)
2.2 (i) Discuss the variation of Fermi level with temperature in an intrinsic semi
conductor (8)
(ii) Describe the method of determining the band gap of an intrinsic
semiconductor (8)
2.3 Discuss the carrier concentration, variation of Fermi level with temperature in
case of p-type and n-type semiconductors for high and low doping levels
(8+6+2)
2.4 What is Hall Effect? Derive an expression for hall coefficient. Describe an
experimental setup for determining the hall coefficient. (2+8+6)

UNIT – III MAGNETIC MATERIALS & SUPER CONDUCTING MATERIALS

PART – A (2 Marks)

1. Define – Magnetic field intensity.
2. Define the terms
(i) Magnetic permeability (ii) Magnetic susceptibility
3. Define the terms
(i) Retentivity (ii) Coercivity
4. What do you mean by magnetic dipole? How will you define dipole
moment?
5 What is domain? What are domain walls?
6. What is Bohr Magneton? Give its value.
7. Distinguish between Dia, Para & Ferro magnetic materials.
8. What is Hysteresis? What are Hysteresis losses?
9. What are Hard & Soft magnetic materials?
10. What are Ferrites? Mention few applications of Ferrites.
11. Define Superconductivity. What are Superconducting materials?
12. What is critical or Superconducting transition temperature?
13. What is Meissner effect?
14. What is persistent current?
15. Distinguish between Type I & Type II superconductors.
16. What are High temperature superconductors? Give examples.
17. What is DC & AC Josephson Effect?
18. What is SQUID?
19. Calculate the critical current in a wire made up of lead having diameter of 1 mm at 4.2K. Critical
temperature of lead is 7.18K & Hc at 0K is 6.5x 104 Amp/m.

PART – B (16 MARKS)

3.1 Distinguish between dia, para, ferro and anti ferro magnetic materials.
Mention their properties and applications (16 Marks)
3.2 Explain domain theory of ferromagnetism. Using that how will you explain the
properties of ferromagnetic materials (16 Marks)
3.3 Explain the magnetic principle involved in data storage and hence explain
the magnetic memories (i) Magnetic tapes (ii) Floppy disk and (iii) Hard disk
(4+4+4+4)
3.4 Discuss the properties of super conductors ( 6 Marks )
Distinguish between Type – I and Type- II Super conductors (6 Marks)
Write a note on high temperature super conductors (4 Marks)
3.5 Write a short note on
(i) Meissner Effect (ii) Josephson Effect (iii) SQUID and (IV) Magnetic levitation
(4+4+4+4)
 

UNIT IV DIELECTRIC MATERIALS

PART – A (2 MARKS)

1. What are dielectric materials?
2. Define dielectric constant.
3. What is dielectric polarisation?
4. Define – Polarisation vector.
5. Distinguish between polar & non-polar molecules.
6. Mention the types of polarisation in dielectric.
7. What do you mean by Lorentz field?
8. Define – Dielectric Loss.
9. Define – Dielectric Breakdown.
10. Mention the various types of breakdown in Dielectrics.
11. What are the properties of Dielectric materials?
12. Mention the applications of Dielectric materials?
13. What is ferro electricity? Give few examples of ferro electric materials.
14. Calculate the electronic polarisability of an isolated Se atom, if the atomic radius of Se atom is
0.12nm.

PART – B ( 16 MARKS)

4.1 Explain the different types of polarization mechanisms involved in dielectric
materials (16 Marks)
4.2 What is meant by local field in a dielectric and how it is calculated for cubic structure? Deduce the
Claussius- Mosotti equation ( 16 Marks)
4.3 What are the different types of dielectric breakdown occurs in a dielectric medium? Discuss in detail,
the various types of dielectric breakdown (2 +14)

UNIT-V NEW ENGINEERING MATERIALS

PART –A ( 2 MARKS)

1. What are metallic glasses?
2. What are the properties of metallic glasses?
3. What are the advantages of using metallic glasses as transformer core
materials?
4. Write any four applications of metallic glasses .
5. What is shape memory effect?
6. What are the characteristics of shape memory alloys?
7. Give any four applications of shape memory alloys.
8. What are the advantages and disadvantages of shape memory alloys?
9. What are Nano phase materials ? Give examples.
10. What are the techniques used for synthesis of nano materials ?
11. What are the properties of nano phase materials?
12. What are the types of carbon nano tubes?
13. What are the structures of carbon nano tubes?
14. What are the properties of carbon nano tubes?
15. What are the applications of carbon nano tubes?

PART- B (16 MARKS)

5.1 Give a detailed account on metallic glasses, their production, types,
properties and applications (16 Marks)
5.2 What are nano-phase materials? Discuss the synthesis, preparation, properties
and applications of nano-phase materials (16 Marks)
5.3 What are shape memory alloys? Write their characteristics. List out any four applications of shape
memory alloys (16 Marks)
5.4 Describe the structure, fabrication, properties and applications of carbon
nano tubes (CNT). (16 Marks)