Jawaharlal Nehru Technological University Anantapur 2010 B.Tech Regular s,e ENGINEERING PHYSICS set - 3 - exam paper
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. |
[8+7] | |
3. |
(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. |
[5+5+5] | |
4. |
(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. |
[5+5+5] | |
5. |
(a) Describe the different methods of acoustic quieting. | |
(b) Describe various method to achieve soundproofing. |
[7+8] | |
6. |
(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]
8
Attachment: |
Earning: Approval pending. |