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MU First Year Engineering (Semester 2)
Applied Physics 2
May 2012
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

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.
[me = 9.1x10-31kg, 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/m2. 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 5cm2 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 (μr = 380) neglecting air gap.
5 M
5 (c) An electron moves in the x-direction with a speed of 1.88x106m/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 10th dark ring is 0.5cm. Calculate radius of curvature R and thickness of film t at the ring.
5 M

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