Attempt any five from the following:

1 (a)
Draw the unit cell and Basic of DC structure.

3 M

1 (b)
Draw the following w.r.t. a cubic unit cell:

(1 1 1) (1 1 1) (1 2 3).

(1 1 1) (1 1 1) (1 2 3).

3 M

1 (c)
Draw a neat labelled Energy band diagram to show the variation of Fermi Level with doping concentration in N-Type semi-conductors.

3 M

1 (d)
Calculate electronic polarizability of Argon atom. Given relative permittivity is 1.0024 at NTP and the gas contains 2.7 × 10

^{25}atoms per m^{3}.
3 M

1 (e)
What are the properties of soft magnetic materials? Briefly explain one application.

3 M

1 (f)
Monochromatic high energy x-rays are incident on a crystal. If 1st order reflection is observed at an angle 3.4°, at what angle would 2nd order reflection be expected.

3 M

1 (g)
A class room has dimensions 20 × 15 × 5 m

^{3}. The reverberation time is 3.5 sec. Calculate the total absorption of its surface and average absorption coefficient.
3 M

2 (a)
Draw the unit cell of HCP. Derive the number of atoms/ unit cell, the c/a ration and the packing fraction. Calculate the ratio of the number of vacancies to the number of atoms when the average energy required to create a vacancy is 0.95 ev at 500k.

8 M

2 (b)
Explain Hall effect & its significance. With a neat diagram derive the expression for the hall voltage & Hall co-efficient.

7 M

3 (a)
Draw the hysteresis loop for a ferromagnetic material. Prove that in a ferromagnetic material, the power loss / unit volume in a hysteresis cycle is equal to the area under the hysteresis loop.

A solenoid consisting of 500 turns and carrying 5amp is 0.5 long. Calculate (i) magneto motive force & (ii) Total flux if the area of the cross section in 0.0004 m

A solenoid consisting of 500 turns and carrying 5amp is 0.5 long. Calculate (i) magneto motive force & (ii) Total flux if the area of the cross section in 0.0004 m

^{2}. (Assume the medium is air).
8 M

3 (b)
With a neat labelled diagram explain the principle, construction and working of a piezoelectric oscillator.

7 M

4 (a)
Explain analysis of crystal structure using Bragg's X-ray spectrometer.

5 M

4 (b)
An Ultrasonic beam of 1 cm wavelength sent by a ship returns from sea bed after 2 sec. If the salinity of sea water at 30°C is 29 gm/lit. Calculate the depth of sea bed at 30°C and the frequency of ultrasonic beam.

5 M

4 (c)
Explain Critical Configuration & find the Critical radius ratio of an ionic crystal for ligancy 6.

5 M

5 (a)
Explain ionic polarization & derive the expression for ionic polarizability.

5 M

5 (b)
In a solid, consider the energy level lying 0.012ev below Fermi level. What is the probability of this level not being occupied by an electron?

Given T=300 Kelvin. K

Given T=300 Kelvin. K

_{s}=1.38×10^{-23}j/K.
5 M

5 (c)
For an intrinsic semiconductor show that the Fermi level lies in the center of the forbidden energy gap.

5 M

6 (a)
What is reverberation? Define Reverberation time. Explain its role in acoustics.

5 M

6 (b)
Explain the principle, construction & working of a LED.

5 M

6 (c)
Describe the types of liquid crystal & their properties.

5 M

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