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B2102 Pages:

2.11 x 1045. What is the minimum uncertainty with which the frequency of the
emitted radiation can be measured?
Differentiate between Fermi-Dirac and Bose-Einstein statistics. Also write down
the distribution function in each case. 5
When a door of height 3 m and width 1.5 m is kept open, the noise intensity level
is found to be 60 dB. How much acoustic power enters through the door?
What is NDT? Describe with the help of a figure any one method of ultrasonic
NDT. ١
What is LASER? Explain the three basic components of a LASER system.
Define acceptance angle. Derive an expression for numerical aperture of an
optical fibre.

PART C

Answer any three questions, each carries 6 marks

Setup the differential equation of motion of a damped harmonic oscillator and
obtain its solution. Derive an equation for displacement of particle for
underdamped oscillations and draw a plot between time and displacement of the
particle.
Explain the formation of Newton’s rings. Describe how wavelength of a
monochromatic source can be determined by forming Newton’s rings.
With reference to a crystal, explain the terms optic axis and principal section.
What is double refraction and explain the difference between positive crystals
and negative crystals.
A subatomic particle of mass m is trapped in a one-dimensional infinite square
well potential of width L. Using Schrédinger equation obtain the energy eigen
values of the particle.

PART D

Answer any three questions, each carries 6 marks

Give an account of any three factors affecting the acoustics of a hall. How are
they remedied?
What is piezoelectric effect? Draw the diagram of a transistor based piezoelectric
oscillator and explain its working. Write down an equation for the frequency of
the above oscillator.
Draw a neat diagram of a He-Ne LASER and explain its construction. Explain its
working with the help of energy level diagram of He and Ne.
How does light propagate in an optical fibre? Distinguish between step index
fibre and graded index fibre. Explain with a block diagram an optical

communication system.
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