Attempt any five from the following:-

1 (a)
Explain the effect on Newton's rings when oil (μ = 1.65) is introduced between the lens (μ = 1.5) and the glass plate (μ = 1.75).

3 M

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

3 M

1 (c)
Explain the terms: Stimulated emission and Population inversion.

3 M

1 (d)
Calculate the De-Broglie wavelength of an electron whose kinetic energy is 120eV.

[m

[m

_{e}= 9.1x10^{-31}kg, h = 6.63x10^{-34}J/sec].
3 M

1 (e)
Distinguish between paramagnetic and ferromagnetic materials.

3 M

1 (f)
Differentiate between step-index fibre and graded-index fibre.

3 M

1 (g)
A magnetic material has magnetization of 2300 A/m and produces a flux density of 0.00314 Wb/m

^{2}. Calculate the magnetizing force H and relative permeability of the material.
3 M

2 (a)
Derive the conditions for a constant thickness film to appear bright and dark when being viewed in reflected light.

8 M

2 (b)
Describe the construction and working of a He-Ne laser with schematic and energy level diagrams.

7 M

3 (a)
What are anti-reflecting films? In costume jewelery, rhinestones (made of glass with μ = 1.5) are often coated with silicon monoxide (μ = 2.0) to make them more reflective. How thick should the coating be to achieve strong reflections for 560nm light, incident normally?

8 M

3 (b)
What is holography? Explain construction and reconstruction of a hologram.

7 M

4 (a)
Develop one dimensional time dependent Schrodinger equation for matter waves.

8 M

4 (b)
Discuss Weiss's theory of ferromagnetism and derive Curie-Weiss's law.

7 M

5 (a)
What is an optical resonator cavity? What role does it play in a laser beam?

5 M

5 (b)
A mild steel ring having a cross-sectional area of 5cm

^{2}and mean diameter 20cm has a coil of 200 turns wound on it. Calculate the reluctance R and the current required to produce flux of 1mWb (μ_{r}= 380) neglecting air gap.
5 M

5 (c)
An electron moves in the x-direction with a speed of 1.88x10

^{6}m/s. If this speed is measured to a precision of 1%, with what precision can you simultaneously measure its position?
5 M

6 (a)
Explain the working principle of pirani gauge?

5 M

6 (b)
Describe the working of scanning electron microscope (SEM) with diagram.

5 M

6 (c)
What are hard and soft magnetic materials? Explain these materials using their characteristic properties and applications.

5 M

7 (a)
What is meant by numerical aperture of an optical fibre? An optical fibre has a numerical aperture of 0.20. Determine the acceptance angle for the fibre in water (μ = 1.33).

5 M

7 (b)
A monochromatic light from He-Ne laser λ = 6328Å is incident normally on a diffraction grating having 6000 lines/cm. Find angles at which first and second order maxima would be observed.

5 M

7 (c)
Newton's rings are observed in reflected light of wavelength 5 x 10

^{-5}cm. The diameter of 10^{th}dark ring is 0.5cm. Calculate radius of curvature R and thickness of film t at the ring.
5 M

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