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MU First Year Engineering (Semester 1)
Applied Physics 1
May 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

Attempt any five from the following:
1 (a) Draw the following in a cubic unit cell (0 1 2), (1 2 3), [1 2 1]
3 M
1 (b) Define the term space lattice, unit cell and lattice parameter.
3 M
1 (c) Determine the lattice constant for FCC lead crystal of radius 1.746 Å and also find the spacing of (2 2 0) plane.
3 M
1 (d) Define: drift current, diffusion current and mobility of charge carriers.
3 M
1 (e) What is the probability of an electron being thermally promoted to conduction band in diamond at 27°C, if bandgap is 5.6 eV wide.
3 M
1 (f) Why soft magnetic materials are used in core of transformers?
3 M
1 (g) Calculate the electronic polarizability of A1. Given number of Air atoms at NTP=2.7×1025/m3 and dielectric constant of Ar=1.0024.
3 M

2 (a) Show that for intrinsic semiconductors the Fermin level lies midway between the conduction band and the valence band. Draw the energy level diagram a function of temperature for n-type of semi-conductor.
8 M
2 (b) Cu has FCC structure. If the interplanar spacing d is 2.08 A° for the set of (111) planes. Find the density and diameter of Cu atom. Give atomic weight of Cu is 63.54.
7 M

3 (a) What is hysteresis? Draw a hysteresis loop for ferromagnetic material and explain the various important points on it. For a transformer which kind of material will you prefer-the one with small hysteresis area or the big one?
8 M
3 (b) Derive Bragg's law. X-ray of unknown wavelength give first order Bragg's reflection at glancing angle of 20° with (2 1 2) planes of cooper having FCC structure. Find the wavelength of X-rays, if the lattice constant for cooper is 3.615 A°.
7 M

4 (a) Discuss Diamond structure with neat diagram and also determine the effective number of atoms / unit cell, co-ordination number and atomic radius in tems of lattice constant.
5 M
4 (b) Classify solids on the basis of energy band diagram.
5 M
4 (c) Explain orientational polarization with suitable diagram and write the mathematical expression of orientational polarizability.
5 M

5 (a) Calculate the number of atoms per unit cell of a metal having the lattice parameter 2.9 A° and density 7.87 gm/cm3. Atomic weight of metal is 55.85. Avogadro number is 6.023×1023/gm mole.
5 M
5 (b) What is Hall effect? Mention its significance. How mobility can be determined by using Hall effect?
5 M
5 (c) The reverberation time is found to be 1.5 second, for an empty Hall and it is found to be 1.0 second when a curtain cloth of 20m2 is suspended at the centre of the Hall. If the dimensions of the hall are 10×8×6m3, calculate the coefficient of absorption of curtain cloth.
5 M

6 (a) Describe principle, construction and working of magnetostriction oscillator to produce ultrasonic waves.
5 M
6 (b) Briefly explain the different types of point defects.
5 M
6 (c) Explain how a voltage difference is generated in a p-n junction when it is used in a photovoltaic solar cell.
5 M

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