Attempt any five

1(a)
Why does an excessively thin film appear to be perfectly dark when illuminated by white light?

3 M

1(b)
A grating has 620 rulings/mm & is 5.05 mm wide. What is the smallest wavelength-interval that can be resolved in the third order at λ = 481 nm?

3 M

1(c)
Why would you recommend use of optical fibre in communication system?

3 M

1(d)
An electron is bound in a one dimensional potential well of width 2A

^{0}but of infinite height. Find its energy values in the ground state and first excited state?
3 M

1(e)
Explain measurement of frequency of AC signal using Cathode Ray Oscilloscope?

3 M

1(f)
Explain the term Stimulated emission & Population inversion?

3 M

1(g)
Define superconductivity, critical temperature & critical magnetic field.

3 M

2(a)
How is Newton's ring experiment used to determine refractive index of liquid medium?

The diameter of 5

The diameter of 5

^{th}dark ring in Newton's ring experiment was found to be 0.42 cm. Determine the diameter of 10^{th}dark ring
8 M

2(b)
An optical fibre has core diameter of 6μ and its core refractive index 1.45. The critical angle is 87°. Calculate- (i) Refractive index of cladding (ii) acceptance angle (iii) The number of modes propagating through fibre when wavelength of light is 1 μm.

7 M

3(a)
With neat energy level diagram, explain principle, construction & working of Nd-YAG laster?

8 M

3(b)
Two plane rectangular pieces of glass are in contact at one edge & are separated at the other end 10 cm away by a wire to form a wedge shaped film. When the film was illuminated by light of wavelength 6000A° , 10 fringes were observed per cm. Determine the diameter of the wire.

7 M

4(a)
Explain the experimental method to determine the wavalength of spectral line using diffraction grating?

5 M

4(b)
Show that electron cannot pre-exist in free state in a nucleus, using uncertainty principle.

5 M

4(c)
Distinguish between type I & type II superconductor?

5 M

5(a)
A diffraction grating used at normal incidence gives a yellow line (λ = 6000A°) in a certain spectral order superimposed on a blue line (λ = 4800A°) of next higher order if the angle of diffraction is sin

^{-1}(3/4), calculate the grating element?
5 M

5(b)
Derive one dimensional time dependent Schrodinger's equation for matter waves?

5 M

5(c)
With neat diagram, explain construction & working of Atomic Force Microscope

5 M

6(a)
Find the de broglie wavelength of (i) an electron accelerated through a potential difference of 182 volts & (ii) 1 kg object moving with a speed of 1 m/s. Comparing the results, explain why is the wave nature of matter not apparent in daily observations?

5 M

6(b)
Derive Bethe's law for electron refraction?

5 M

6(c)
What are Carbon nano tubes? Explain properties of Nano tubes?

5 M

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