I B.Tech - Regular Examinations, June 2009
First Year
APPLIED PHYSICS - SET NO: 3
(Regulation 2007)
Time : 3 hours |
Maximam Marks:80 |
Answer any FIVE Questions
1. (a) State and explain Bragg’s law.
(b) Describe with suitable diagram, the powder method for determination of crys-
tal structure.
(c) A beam of X-rays of wavelength 0.071 nm is diffracted by (1 1 0) plane of rock
salt with lattice constant of 0.28 nm. Find the glancing angle for the second
order diffraction.
2.(a) Show that the wavelength (λ) of an electron accelerated by a potential differ-
ence of V volts, is λ= 12.27/√V °A. for non-relativistic case..
(b) Describe an experiment with a neat diagram, to establish the wave nature of
electrons.
(c) Calculate the velocity and kinetic energy of an electron of wavelength 1.66 °A.
3.(a) What is Bloch theorem? Explain.
(b) Discuss Kronig-Penney model for the motion of an electron in a periodic potential
4. (a) Describe the phenomenon of electronic polarization and obtain an expression
for electronic polarizability.
(b) Write notes on:
i. Ferro-electricity and
ii. Piezo-electricity.
5. (a) Explain in detail the following
i. Meissner effect and
ii. Penetration depth of a superconductor.
(b) What are hard and soft superconductors?
(c) Discuss the important applications of super conductors.
6. (a) What is population inversion relating to laser action? Explain.
(b) Distinguish between homo-junction semiconductor laser and hetero-junction
semiconductor laser.
(c) Calculate the wavelength of emitted radiation from GaAs which has a band
gap of 1.44 eV.
7.((a) Distinguish between light propagation in (i) step index and (ii) graded index
optical fibers.
(b) Discuss the various advantages of communication with optical fibers over the
conventional coaxial cables.
(c) Calculate the refractive indices of core and cladding of an optical fiber with a
numerical aperture of 0.33 and their fractional difference of refractive indices
being 0.02.
8.(a) Write a detailed note on nanoscience.
(b) Why nanomaterials exhibit different properties? Explain.
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