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SPPU First Year Engineering (Semester 1)
Engineering Physics
December 2015
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

Solve any one question from Q1 and Q2
1 (a) Prove that in Newton's rings by reflected light the diameter of dark ring is proportional to square root of a natural number.
6 M
1 (b) Explain any two factors affecting the acoustics of a hall and remedies on that.
3 M
1 (c) The classroom has dimension, 20×15×5 m3. The reverberation time is 3.5 sec. Calculate the total absorption of its surface and the average absorption.
3 M

2 (a) Explain piezoelectric effect. Explain how piezoelectric oscillator is used to produce ultrasonic waves, with the help of a neat circuit diagram.
6 M
2 (b) The resultant amplitude of a wave when monochromatic light is diffracted from a single slit is $$E_\theta = E_m = \dfrac {\sin \alpha }{\alpha}$$. Then derive the condition of minima.
3 M
2 (c) A soap film having refractive index 1.33, and thickness 5×10-5 cm is viewed at an angle of 35° to the normal. Find the wavelength of light in the visible spectrum which will be absent from the reflected light.
3 M

Solve any one question from Q3 and Q4
3 (a) Explain construction and working of Ruby Laser with the help of energy level diagram.
6 M
3 (b) What is Fermi level? Explain Fermi-Dirac probability distribution function.
3 M
3 (c) Plane polarized light of wavelength 5×10-5 cm is incident on a piece of quarter cut parallel to the optic axis. Find the least thickness of quarter for which the O-ray and E-ray combine to from plane polarized light.
Given: μ0=1.5442, μe=1.5633.
3 M

4 (a) Explain Hall Effect. Derive the equation of Hall voltage and Hall coefficient.
6 M
4 (b) State and prove Malus law.
3 M
4 (c) Calculate the number of acceptors to be added to a germanium sample to obtain the resistivity of 20 Ω cm.
Given: μ=1700cm2/V.sec.
3 M

Solve any one question from Q5 and Q6
5 (a) Deduce Schrödinger's time independent wave equation.
6 M
5 (b) Define phase (wave) velocity. Show that the phase velocity of matter wave is greater than the velocity of light.
4 M
5 (c) Calculate the deBroglie wavelength of electron of energy 1 keV.
3 M

6 (a) State Heisenberg's uncertainty principle and prove it by thought experiment of electron diffraction at a single slit.
6 M
6 (b) What is wave function? Explain what is normalization of wave function.
4 M
6 (c) The lowest energy of an electron trapped in a rigid box is 4.19 eV. Find the width of the box in A.U.
3 M

Explain:
7 (a) (i) Critical field.
3 M
7 (a) (ii) Meissner effect.
3 M
7 (b) Explain any two properties of nano-particles in brief.
4 M
7 (c) Explain the applications of nano-particles in electronic industry.
3 M

8 (a) Explain the synthesis of nano-particles by chemical method in colloidal form with diagram and example.
6 M
8 (b) Explain in brief the BCS theory of superconductivity.
4 M
8 (c) Give any six applications of superconductivity.
3 M

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