JNTU previous year question paper, B.Tech Supplementary Exam, Engineering physics set-III

JNTU B.Tech Supplimentary Examinations, Aug/Sep 2008




1. (a) What is meant by interference of light? State the fundamental conditions for

the production of interference fringes.

(b) Explain with necessary theory the formation of Newton’s rings and measure-

ment of wavelength of light.


2. (a) Explain why the sky appears blue and red at different times during a day.

(b) Discuss how the circular and elliptical polarized lights can be produced.

(c) The refractive index of calcite crystal is 1.658 for ordinary ray and it is 1.486

for extra-ordinary ray. A slice having thickness 0.9 ×10?4 cm is cut from the

crystal. For what wavelengths this slice behave as a

i. quarter wave plate,

ii. half wave plate?


3. (a) Explain superconducting phenomenon.

(b) Distinguish between Type-I and Type-II superconductors.

(c) Discuss various applications of superconductors.


4. (a) Explain the terms:

i. Absorption.

ii. Spontaneous emission.

iii. Stimulated emission.

iv. Pumping mechanism.

v. Population inversion.

vi. Optical cavity.

(b) Mention the medical applications of lasers.


5. (a) Explain the principle behind the functioning of an optical fibre.

(b) Derive an expression for acceptance angle for an optical fibre. How it is related

to numerical aperture?

(c) An optical fibre has a numerical aperture of 0.20 and a cladding refractive

index of 1.59. Find the refractive index of core and the acceptance angle for

the fibre in water which has a refractive index of 1.33.


6. (a) What are the characteristics of soft magnetic materials?

(b) What is ferro-magnetic curie temperature? Discuss the behaviour of a ferro-

magnetic material below the Curie temperature.

(c) The magnetic induction in the interior of a certain solenoid has the value of

6.5 ×10?4 T when the solenoid is empty. When it is filled with iron, the

induction becomes 1.4 T. Find the relative permeability of iron.


7. (a) State and explain Bragg’s law.

(b) Describe with suitable diagram, the powder method for determination of crystal structure.

(c) A beam of X-rays of wavelength 0.071 nm is diffracted by (110) plane of rock

salt with lattice constant of 0.28 nm. Find the glancing angle for the second order diffraction.


8. (a) Distinguish between Frenkel and Schottkey defects.

(b) Derive an expression for the energy change due to creation of vacancies inside

a solid.

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