**Anna University B.E PH1X01: ENGINEERING PHYSICS (MODEL) Question paper**2008 Anna University B.E PH1X01: ENGINEERING PHYSICS (MODEL) Question paper

Course: B.E University: Anna University

(Common to all Branches of Engineering and Technology)

Regulation 2004

Time: 3 Hours Maximum Marks: 100

(Answer all Questions)

PART –A (10x2=20 marks)

1. Noise level inside a room with printer operating is found to be 80 dB. Find the noise level produced by the printer alone, if the background noise without the printer is 73 dB.

2. What is a unit cell? How many lattice parameters are required to describe a cubic lattice?

3. A monochromatic source of light is used to get circular fringes in Michelson’s interferometer. When the movable mirror is moved by 0.06 mm, a shift of 200 circular fringes is observed. Find the wavelength of light used?

4. What is the principle of laser and give the important requisites for laser action to take place.

5. State Wiedemann-Franz law.

6. The Fermi energy of Cesium is 1.55 eV. Calculate the number of conduction electrons in 1 cm3 of the metal.

7. With increase in temperature the resistivity of semiconductors decreases, while that of metals increases. Give reasons.

8. Explain isotope effect in superconductors.

9. What are metallic glasses?

10. What are the requirements of good insulating materials?

PART –B (5x16 = 80 marks)

11. a) i) Explain the various factors affecting acoustics of buildings and their remedies. (8 )

b) ii) What is magnetostriction effect? With a neat circuit diagram, describe the production of ultrasonic waves by magnetostriction method. (8 )

(or)

b) i) Describe simple cubic, body centered cubic and face centered cubic structures with examples and calculate the atomic packing density. (12)

ii) NaCl crystal has fcc lattice. The density of NaCl is 2.18 g/cm3. Calculate the distance between the sodium and chlorine ions. (Atomic weight of sodium is 23 and atomic weight of chlorine is 35.5). (4)

12. a) i) Describe the construction and working of Michelson’s interferometer.

Explain the method of determination of wavelength of monochromatic source of light. (12)

ii) Explain fibre optic based displacement sensor. (4)

(or)

b) i) With necessary theory explain the construction and working of CO2 laser. (12)

ii) Discuss the classification of optical fibres based of refractive index profile. (4)

13. a) i) Solving Schrodinger’s time independent wave equation find the energy eigenvalues of a particle moving freely inside an one – dimensional box. (12)

ii) In a Compton experiment the wavelength of the incident photon is 1.325?,

whereas that of the scattered photon is 1.351?. Find the angle through which the photon is scattered and also calculate the kinetic energy of the recoiling electron. (4)

(or)

b) i) Derive an expression for density of energy states. Obtain an expression for Fermi

energy in metals at T = 0 K. (12)

ii) Aluminum is a trivalent metal. Its electrical conductivity at room temperature is 3.8x107 O-1m-1. The atomic weight and density of aluminum are 27 and 2700 kg/m3 respectively. Calculate the mean free path of the conduction

electrons in aluminum at room temperature. (4)

14. a) i) Derive an expression for electrical conductivity of an intrinsic semiconductor.

Describe the experimental method of determination of bandgap of a

semiconductor (16)

(or)

b) i) Explain with a sketch the variation of Fermi level with temperature and doping

concentration in an N-type semiconductor . (12)

ii) Explain Type I and Type II superconductors. (4)

15. a) i) What is meant by internal field in dielectrics? Obtain Clasius- Mosotti equation and explain how it can be used to determine the dipole moment of polar molecules. (12)

ii)Explain shape memory alloys. (4)

(or)

b) i) Explain the non-destructive testing method of materials by Liquid penetrant method. (8 )

ii) Draw the block diagram of ultrasonic flaw detector and explain how it is used for detecting defects in materials. (8 )