APPLIED PHYSICS ECE JNTU previous years question papers

APPLIED PHYSICS
Common to BME, IT, ICE, E.COMP.E, ETM, E.CONT.E, EIE, CSE, ECE,
CSSE, EEE

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

1. (a) Explain the following:
i. electrical conductivity and
ii. Fer mi energy.
(b) Explain briey the classical free electron theory of metals.
(c) On the basis of band theory how the crystalline solids are classi_ed into metals, semiconductors and insulators? [4+6+6]

2. (a) What are the di_erences between `photography' and `holography'?
(b) What is recording and reconstruction of a hologram? Explain. [6+10]

3. (a) What are Miller indices? How are they obtained?
(b) Show that FCC is the most closely packed out of the three cubic structures by calculating the packing factors.
(c) Copper has FCC structure and the atomic radius is 0.1278 nm. Calculate the interplanar spacing for (1 1 1) and (3 2 1) planes. [4+8+4]

4. (a) Describe thevari ous methods to achieve population inversion relating to lasers.
(b) With the help of a suitable diagram, explain the principle, construction and working of a semiconductor laser. [6+10]

5. (a) Write a note on extrinsic semiconductors.
(b) Derive an expression for the carrier concentration in p-type extrinsic semiconductors. [6+10]

6. (a) What is Planck's quantum theory? Explain in detail.
(b) Write short notes on:
i. de Broglie hypothesis and
ii. Heisenberg's uncertainty principle. [8+8]

7. (a) Why nanomaterials exhibit di_erent properties? Explain.
(b) Describe the vari ous types of carbon nanotubes. [10+6]

8. (a) Explain the following:
i. Polarization vector and
ii. Electric displacement.
(b) Deduce an expression for Lorentz _eld relating to a dielectric material.
(c) The radius of the helium atom is 0.55 _A.Calculate the polarizability of He and its relative permittivity. The number of He atoms in a volume of one metre cube is 2.70 _ 1025 atoms. [permittivity of free space = 8.85 _10&12 F/m]
[4+8+4]

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