1
Define drift velocity. How is it different from thermal velocity of an electron?

2 M

2
Define Fermi level.

2 M

3
Write an expression for electrical conductivity of an intrinsic semiconductor.

2 M

4
What are the differences between elemental semiconductor and compound semiconductor?

2 M

5
Every magnetic material has an intrinsic diamagnetism. Explain.

2 M

6
State the use of magnetic levitation.

2 M

7
Define dielectric constant.

2 M

8
Distinguish between dielectric loss and dielectric breakdown.

2 M

9
What is shape memory effect?

2 M

10
What are the different crystalline forms of carbon?

2 M

Answer any one question from Q11 (a) & Q11 (b)

11 (a)(i)
List the drawbacks of classical free electron theory.

4 M

11 (a)(ii)
Obtain Wiedemann Franz law using the expression of electrical and thermal conductivity and find the expression for Lorentz number.

4 M

11 (a)(iii)
The density of Silver is 10.5 × 10

^{3}kg/m^{3}. The atomic weight of silver is 107.9. Each silver atom provides one conduction electron. The conductivity of silver at 20°C is 6.8×10^{7}ohm^{-1}m^{-1}. Calculate the density of electron and also the mobility of electrons is silver.
4 M

11 (a)(iv)
Calculate the electric and thermal conductivities of a metal with the relaxation time of 10

^{-14}second at 300 K. The electron density is 6×10^{26}m^{-3}.
4 M

11 (b)(i)
Derive an expression for electrical conductivity based on Quantum theory.

8 M

11 (b)(ii)
Write the expression for Fermi distribution function and explain with suitable diagram. How does it vary with temperature?

4 M

11 (b)(iii)
Calculate the Fermi energy and Fermi temperature in a metal. The Fermi velocity of electrons in the metal is 0.86×10

^{6}m/s.
4 M

Answer any one question from Q12 (a) & Q12 (b)

12 (a) (i)
Assuming the Fermi-Dirac distribution derive an expression for the concentration of electrons per unit volume in the conduction band of an intrinsic semiconductor.

12 M

12 (a) (ii)
Find the intrinsic carrier concentration and position of Fermi energy level I in Silicon with respect to the VB edge. Given m

_{h}=0.92 m_{0}; m_{e}=0.49 m_{0}; N_{c}=2.21×10^{25}/m^{3}N_{v}=8.60×10^{24}/m^{3}and T=300 K.
4 M

12 (b) (i)
With neat sketches, explain how Fermi level varies with impurity concentration and temperature in both p-type and n-type semiconductors.

8 M

12 (b) (ii)
What is Hall effects? Describe an experimental arrangement to measure the Hall co-efficient.

8 M

Answer any one question from Q13 (a) & Q13 (b)

13 (a)(i)
Explain the domain theory of Ferromagnetism. Using that theory, explain the formating of hysteresis in ferromagnetic materials.

8 M

13 (a)(ii)
The magnetic field strength of Silicon is 1500 A/m. If the magnetic susceptibility is -0.3 ×10

^{-5}, calculate the magnetization and flux density in Silicon.
4 M

13 (a)(iii)
Differentiate a soft magnetic material from a hard magnetic material.

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13 (b) (i)
Explain any four properties of superconductors.

8 M

13 (b)(ii)
Differentiate between Type I and Type II superconductors.

4 M

13 (b)(iii)
Describe high temperature superconductors.

4 M

Answer any one question from Q14 (a) & Q14 (b)

14 (a)(i)
Explain electronic polarization in atoms and obtain an expression for electronic polarizability in terms of the radius of atoms.

10 M

14 (a)(ii)
If a NaCI crystal is subjected to an electric field of 1000 V/m and the resulting polarization is 4.3×10

^{-8}C/m^{2}, calculate the relative permittivity of NaCI. Take the value ε_{0}=8.86×10^{-12}Fm^{-1}.
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14 (a)(iii)
The number of atoms in a volume of one cubic meter of hydrogen gas is 9.8×10

^{25}. The radius of hydrogen atom is 0.53 Å. Calculate, the polarizability and relative permittivity.
4 M

14 (b)(i)
What is meant by Internal field? Obtain an expression for internal field using Lorentz method.

8 M

14 (b)(ii)
A solid contains 5 ×10

^{28}identical atoms per m^{3}each with a polarizability of 2×10^{-40}Fm^{2}. Assuming that internal field is given by the Lorentz relation, calculate the ratio of internal field to the applied field ε_{0}=8.854×10^{-12}Fm^{-1}
4 M

14 (b)(iii)
The dielectric constant of water is 80. Is water a good dielectric? Is it useful for energy storage in capacitors? Justify your answer.

4 M

Answer any one question from Q15 (a) & Q15 (b)

15 (a)(i)
What are shape memory alloys? Describe the characteristics of shape memory alloys.

8 M

15 (a)(ii)
List out any four applications of shape memory alloys.

4 M

15 (a)(iii)
Mention any two advantages and two disadvantages of SMAs.

4 M

15 (b) (i)
What are nanoparticles? Explain how nanoparticles can be produced using ball-milling technique.

8 M

15 (b) (ii)
Describe the mechanical, chemical and magnetic and properties of nanoparticles.

8 M

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