JNTU Applied Physics Exam Paper May June 2008
1. (a) Explain the forces between the two interacting atoms when they are brought nearer to form a molecule.
(b) Derive the expression for the equilibrium spacing of two atoms for which the potential energy is minimum.
2. (a) Explain de-Broglie hypothesis.
(b) Describe G.P.Thomson’s experiment in support of this hypothesis.
(c) Find the wavelength associated with an electron rose to a potential 1600 V.
3. (a) Distinguish between Drude-Lorentz theory and Sommerfeld’s theory of metals.
(b) Define Fermi level of electron.
(c) Find the drift velocity of free electrons in a copper wire of cross-sectional area 10 mm2, when the wire carries a current of 100 A. Assume that each copperatom contributes one electron to the electron gas. [Density of copper = 8.92× 103 kg/m3, Atomic weight of copper = 63.5 and Avogadro’s number = 6.02× 1026 per k-mol]
4. (a) Explain the following:
i. Dielectric constant
ii. Electric susceptibility,
iii. Electric Polarization and
(b) Write notes on:
i. Ferro-electricity and
5. (a) Explain the critical parameters and their significance in superconductors.
(b) Write notes on:
i. isotope effect and
ii. energy gap, in superconductors.
(c) A Josephson junction having a voltage of 8.50 μV across its terminals, then
calculate the frequency of the alternating current. [Planck’s constant = 6.626×10−34 J-sec]
6. (a) Explain the characteristics of a LASER.
(b) Describe the construction and working of Ruby laser.
(c) Write any four applications of laser.
7. (a) Derive an expression for the ‘numerical aperture’ of an optical fiber.
(b) Explain the advantages of optical communication system.
(c) The numerical aperture of an optical fiber is 0.39. If the difference in the refractive indices of the material of its core and the cladding is 0.05, calculatethe refractive index of material of the core, when the light is launched into it in air.
8. (a) Write a detailed note on nanoscience and nanotechnology.
(b) Write the important applications of nanomaterials in medicine.