STUPIDSID
Attempt any five from the following
1(a)
Draw (a) (1 1 2) (b) (0 4 0) (c) [0 4 0] with reference to a cubic unit cell
3 M
1(b)
What is the probability of an electron being promoted to the conduction band in diamond at 27°C, if the bandgap is 5.6 eV wide?
3 M
1(c)
Define drift current, diffusion current and mobility of charge carriers.
3 M
1(d)
What is dielectric polarization and dielectric susceptibility? Write the relation between them.
3 M
1(e)
State and explain Ohm's law in magnetic circuit.
3 M
1(f)
Write Sabine's formula and explain the terms used in it.
3 M
1(g)
Calculate the length of an iron rod which can be used to produce ultrasonic waves of 20kHz Given - Y = 11.6 × 1010N/m2, ρ = 7.23 × 103 kg/m3
3 M
2(a)
Explain formation of energy bands in solids and explain classification on the basis of energy band theory.
8 M
2(b)
Zn has hcp structure. The nearest neighbour distance is 0.27 nm. The atomic weight of Zn is 65.37. Calculate the volume of unit cell, density and atomic packing fraction of Zn.
7 M
3(a)
What is hysteresis? Draw a hyteresis for ferromagnetic material and explain various important parameters.
A magnetic material has a magnetization of 2300 A/m and produces a flux density of 0.00314 wb/m2, Calculate magnetizing force and permeability of the material.
A magnetic material has a magnetization of 2300 A/m and produces a flux density of 0.00314 wb/m2, Calculate magnetizing force and permeability of the material.
8 M
3(b)
Explain the statement 'crystal act as three dimesional grating with X-rays'.
Monochromatic X-ray beam of wavelength &lambda = 5.8189 A° is reflected strongly of lattice constant 3A°. Determine Miller indices of the possible reflecting planes.
Monochromatic X-ray beam of wavelength &lambda = 5.8189 A° is reflected strongly of lattice constant 3A°. Determine Miller indices of the possible reflecting planes.
7 M
4(a)
Define ligancy. Find the value of critical radius ratio for ligancy 4.
5 M
4(b)
An impurity of 0.01 ppm is added to Si. The semiconductor has a resistivity of 0.25Ωm at 300K. Calculate the hole concentration and its mobility. Atomic weight of Si is 28.1, density of Si=2.4×103kg/m3
5 M
4(c)
Explain the origin of electronic, ionic and orientational polarization and temperature dependence of respective polarizability.
5 M
5(a)
The density of copper is 8980kg/m3 and unit cell dimension is 3.61 A°. Atomic weight of copper is 63.54. Determine type of crystal structure. Calculate atomic radius and interplanner spacing of (1 1 0) plane.
5 M
5(b)
What is Hall effect? Derive expression for Hall voltage with neat labelled diagram.
5 M
5(c)
Explain how the reverberation time is affected by (i) size (ii) nature of wall surface (iii) audience in an auditorium.
5 M
6(a)
Estimate the ratio of vacancies at (i) -119°C (ii) 80°C where average required to create vacancy is 1.8eV.
5 M
6(b)
How a p-n junction diode is used to generate a potential, difference in a photovoltaic solar cell?
5 M
6(c)
Explain with neat lebelled diagram the construction and working of a piezoelectric oscillator.
5 M
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