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B2802 Pages: 2

What should be the minimum size of cell in phase space according to classical
and quantum mechanics?
A quartz crystal of length 2mm is vibrating at resonance. Calculate the
fundamental frequency of vibration, if Young’s modulus Y = 8.5x10!° N/m? and
density = 3000kg/m’.
A cinema hall has a volume of 8000 ന്‌. It is required to have a reverberation of
2s. What should be the total absorption of the hall? - ,
Point out the differences between spontaneous emission and stimulated emission.
Why fiber optic communication system is preferred over other types of
communication techniques.
PART C
Answer any three questions, each question carries 6 marks.

Write down differential equation for a damped harmonic oscillator and obtain its
solution. Show that, in underdamping condition, amplitude is an exponentially
decaying quantity.
Show that the radii of different dark rings in Newton’s Rings are proportional to
square root of integers. Explain with necessary theory, how the refractive index of
the given liquid is determined using Newton’s Rings arrangement.
Distinguish between positive and negative crystals. Explain the construction of
quarter wave plate and half wave plate. Also obtain the expressions for their
thickness.
State uncertainty principle and explain why electrons cannot be present in the
nucleus.
PART C
Answer any three questions, each question carries 6 marks.

Express the numerical aperture of a step index fiber in terms of the refractive
index of core and cladding. Also write any two technological applications of
optical fibres.

Explain the production of ultrasonic waves by magneto striction method.

Explain the terms reverberation and reverberation time. Discuss the factors on
which the reverberation time depends on, and deduce Sabine’s formula.

Explain the principle involved in photo detection. Describe the working of any

two commonly used photo detectors.
111.

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