I. Answer any tour of the following
PHYSICS
PAPER
SECTION A (10x4=40)
Distinguish between resolving power and dispersive power of a grating. What should he the resolving power of a grating to resolve two closely spaced wavelengths 4500A and 45100
What is holography and how is it different from ordinary photography?
The focal length of achromatic doublet made up of crown and flint glasses is 15 cm. Calculate the focal length of converging and diverging lenses of doublet if dispersive Power of crown and flint glasses are 0.01506 and 0.02427 respectively.
Explain the term phase velocity and group velocity. What are its significance?
Deduce an expression for the moment of inertia of a diatomic molecule a distance about an axis passing through the centre of mass and perpendicular to the bond length and also along the bond length.

2. Discuss the motion of particle under a central force field. Find the condition under which the orbit will be ellipse or parabola or hyperbola.(20)
An artificial earth satellite is travelling at an altitude of 150 km above the earth's surface, where 9.5 m/sec2, Calculate the speed of the satellite. (radius of the earth· 6000 km)

3 Derive the formula for variation of mass with velocity.
A rod of length I m in a spaceship is moving with a velocity of 0.3C relative to the earth Calculate its length as measured by an observer first on the spaceship and on the earth.
Deduce an expression for total energy' of a simple harmonic oscillator. Show that total energy remains independent of time and displacement. Write a note on the effect of damping on the total energy of oscillator. 20

4. Discuss the principle of French half period zones and explain how these are used in the
construction of a zone plate. Show that zone plate has several foci.(20)
Discuss briefly some application of Michelson enter-ferro-meter.
Lycopodium spores which have an average diameter of 30 Um are dusted on a glass plate, If parallel light of lambda=589 nm is passed through the plate, what is the angular radius of first diffraction maximum

SECTION B
5. Answer any four of the following:

If in the LCR serious circuit. a.c. voltmeter reads 30 volt across the resistor. 80 volt across the inductance, 40 volt across the condenser, what is the applied cmf
A condenser of capacity 1 microfarad and inductance of 0.2 Henri and resistance of 800 ohm are Joined on series. Is the circuit oscillatory?
An electric dipole of two opposite charges of 10 coulomb separated by 4cm place in an external electric field of strength 10 -5,volts/m. Find the work required to turn the dipole in the reverse direction.
What is the physical significance of pointing vector Deduce an expression for the intensity of electromagnetic wave propagating in free space.
Two magnets having magnetic moments M and root 3M are joined to form a cross. If this combination is suspended freely in a uniform horizontal magnetic field. what will be its equilibrium orientation in this field?
6 Write down the Poisson's equation for a homogeneous dielectric medium. What is the condition necessary to derive Laplace equation from Poisson's equation? A 50 volt AC source of frequency 500 Hz is connected to an LCR circuit with L=8.1 millihenri: C 12.5 newF: R 20 om all connected in series, Find the potential across the resistance.
State Kirchhoffs laws for steady current and prove them. Apply the Kirchhoffs laws to Wheat stones network and show that R/N 20

7 Using Maxwell's equations,obtain the velocity of an electro magnetic wave in vacuum.

What is Wien's displacement law Show that sun radiates maximum energy in the visible region whereas earth radiates in region.

8 Derive the equation of state for a van der Wall's gas and calculate values of critical
constants. 10
What is entropy ?How is it related to disorder in the system
Discuss Einstein's Theory of specific beat of solids. Compare and contrast witt Debye's
theory
useful constants:
h =6.62 X lO-34 joule-sec
1.65 x 10 -19 coulomb
c=3.0 x 10 8 m/sec
1/4pie G=9x109Nm2/coulomb
new 0=4piex10 weber/amp.m