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Jawaharlal Nehru Technological University Anantapur 2009 B.Tech Regular s,e ENGINEERING PHYSIC set - 3 - Question Paper

Wednesday, 29 May 2013 05:10Web

Code No: 09A1BS02    R09    Set No. 3

I B.Tech Regular Examinations,June 2010 ENGINEERING PHYSICS Common to CE, ME, CHEM, BME, IT, MECT, MEP, AE, BT, AME, ICE, E.COMP.E, MMT, ETM, EIE, CSE, ECE, EEE Time: 3 hours    Max Marks: 75

Answer any FIVE Questions All Questions carry equal marks

1.    (a) Explain Fermi-Dirac distribution function. Illustrate the effect of temperature

on the distribution.

(b) Derive an expression for density of states of an atom.    [8+7]

2.    (a) Derive the expressions for:

i.    Acceptance angle and

ii.    Numerical aperture of an optical fiber.

(b) Describe the different types of fibers by giving the refractive index profiles and

propagation details.



(a) What are Brillouin zones? Explain using E-K diagram.

(b) Define effective mass of an electron. Explain its physical significance.

(c) What is a hole? List out the properties of a hole.



(a) Write notes on point defects in crystals..

(b) Derive the expression for the density of Frenkel defects in a metallic crystal.

(c) What is Burgers vector? Explain.



(a) Describe the different methods of acoustic quieting.

(b) Describe various method to achieve soundproofing.



(a) Explain the terms:

i.    Magnetic induction,

ii.    Magnetic susceptibility,

iii.    Permeability of a medium and

iv.    Intensity of magnetization.

(b)    What are hard and soft magnetic materials? Give their characteristic properties and applications.

(c)    A paramagnetic material has a magnetic field intensity of 104 amp/m. If the susceptibility of the material at room temperature is 3.7 x 10-3. Calculate the magnetization and flux density of the material.    [6+5+4]

7. (a) What do you understand by Miller indices of a crystal plane?

(b)    Show that in a cubic crystal the spacing (d) between consecutive parallel planes of Miller indices (h k l) is given by d = a (h2 + k2 + l2)-1/2.

(c)    NaCl crystals have FCC structure. The density of NaCl is 2.18 gm/cm2. Calculate the distance between two adjacent atoms. (Molecular weight of NaCl = 58.5).    [4+7+4]

8. (a) Derive an expression for density of electrons in intrinsic semiconductors.

(b)    Explain the variation of Fermi level with temperature in the case of p-type semiconductors.

(c)    If the effective mass of holes in a semiconductor is 5 times that of electrons, at what temperature would the Fermi level be shifted by 15% from the middle of the forbidden energy gap? [Given that the energy gap for the semiconductor is 1.20 eV].    [7+4+4]



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