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B.E./B.Tech. DEGREE EXAMINATIONS, MAY/JUNE 2010
Regulations 2008
First Semester
Common to all branches
**PH2111 Engineering Physics I**
Time: Three Hours Maximum: 100 Marks
Answer ALL Questions
Part A - (10 x 2 = 20 Marks)
1. Mention any two properties of ultrasonic waves.

2. What i s the principle of pulse echo system?

3. What are the conditions needed for laser action?

4. What is holography?.

5. De¯ne acceptance angle of a ¯bre.

6. Give the applications of the ¯bre optical system.

7. Calculate de Broglie wavelength of an electron moving with velocity 107 m/s.

8. Explain degenerate and non-degenerate states.

9. Calculate the ¯rst and second nearest neighbor distances in the body centered cubic unit

cell of sodium, which has lattice constant of 4:3 £ 10¡10 m.

10. What is meant by Frenkel imperfection?

Part B - (5 x 16 = 80 Marks)
11. (a) (i) What are magnetostriction and piezoelectric e®ect? (4)

(ii) Write down the complete experimental procedure with a neat circuit diagram of

producing ultrasonic waves by piezoelectric e®ect. (12)

OR

11. (b) (i) What is an acoustic grating? How is it used in determining the velocity of

ultrasound?

(2 + 6)

(ii) Explain the process of non-destructive testing of materials using ultrasonic waves

by pulse-echo method. (8)

12. (a) (i) Derive the relation between the probabilities of spontaneous emission and stimu-

lated emission in terms of Einstein's coe±cients. (8)

(ii) Explain the following pumping mechanisms.

(1) optical and

(2) electric discharge. (8)

OR

12. (b) (i) With a neat sketch, explain the construction, principle and working of CO2 laser.

(14)

(ii) Mention four applications of lasers in materials processing.

(2)

13. (a) (i) Explain the basic structure of an optical ¯bre and discuss the principle of trans-

mission of light through optical ¯bres. (5)

(ii) Derive an expression for numerical aperture. (5)

(iii) Brie°y discuss a technique of optical ¯bre drawing. (6)

OR

13. (b) (i) With a neat diagram, give an account on displacement sensors. (8)

(ii) Give an elaborate account on losses in optical ¯bres. (8)

14. (a) (i) What is Compton e®ect? Derive an expression for the change in wavelength

su®ered by an X-ray photon, when it collides with an electron. (2 + 12)

(ii) An electron at rest is accelerated through a potential of 2 kV. Calculate the de

Broglie wavelength of matter wave associated with it. (2)

OR

14. (b) (i) Solve the Schrodinger's wave equation for a free particle of mass m moving within

a one dimensional potential box of width L to obtain eigenvalues of energy and

eigenfunctions.

(11)

(ii) Find the eigenvalues of energies and eigenfunctions of an electron moving in a

one dimensional potential box of in¯nite height and 1 ºA of width. Given that m

= 9.11 £10¡31 kg and h = 6.63 £10¡34 J. (5)

15. (a) (i) What are Miller indices? Mention the steps involved to determine the Miller

indices with example. (2 + 4)

(ii) The material zinc has HCP structure. If the radius of the atom is

1

4

th of the

diagonal of hexagon, calculate the height of the unit cell in terms of atomic

radius.

(2)

(iii) Show that the packing factor for HCP i s 74% . (8)

OR

15. (b) (i) What i s Burger vector? (2)

(ii) Draw Burger circuit indicating Burger vector for edge dislocation and screw dis-

location. (4+4)

(iii) Certain defects in crystals improve the properties of crystals. Explain. (6)

**PH2111 Engineering Physics I**

**THIS FOR YOUR REFERENCE PURPOSE ONLY**

**PH2111 Engineering Physics I**

2. Compare transmission and re°ection modes of non destructive testing using ultra-

sonics.

3. Why is population inversion necessary to achieve lasing?

4. How is electrons and holes con¯nement made in the active region of heterojunction

laser?

5. What are the di®erent types of classi¯cation of optical ¯bres?

6. Explain dispersion in an optical ¯ber.

7. De¯ne blackbody and blackbody radiation.

8. What i s meant by wave function?

9. An element has a HCP structure. If the radius of the atom is 1.605ºA, ¯nd the height

of unit cell.

10. What i s meant by a `Schottky pair'?

piezoelectric crystal. (16)

OR

11. (b) (i) With a neat diagram, discuss the principle and inspection method of ul-

trasonic °aw detector. (12)

(ii) Calculate the velocity of ultrasonic waves in water using acoustic grat-

ing. The frequency of the ultrasonic wave generated by transducer is 2

MHz. The di®raction angle measured i s 8'45" in the third order di®rac-

tion pattern. Wavelength of laser light used in this experiment is 6328ºA.

(4)

12. (a) Discuss the Einstein's theory of stimulated absorption, spontaneous and stim-

ulated emission of radiation. What are the conditions for light ampli¯cation?

(16)

OR

12. (b) (i) What is hologram? What are the necessary steps involved in recording

and reconstruction of a hologram? (12)

(ii) Compare holography with photography. (4)

13. (a) (i) Explain the basic structure of an optical ¯bre and discuss the principle of

transmission of light through optical ¯bres. (5)

(ii) Derive an expression for numerical aperture. (5)

(iii) Brie°y discuss a technique of optical ¯bre drawing. (6)

OR

13. (b) Explain the concept of optical ¯ber sensors and describe in detail about any

two sensors. (6 + 10)

14. (a) (i) What is meant by matter wave? (2)

(ii) Derive an expression for the wavelength of matter wave. (8)

(iii) Describe an experiment that veri¯es the existance of matter waves. (6)

OR

14. (b) Solve Schrodinger's wave equation for a particle in a box (one dimensional)

and obtain the energy and eigen function. (16)

15. (a) (i) De¯ne atomic packing factor. (2)

(ii) Calculate the number of atoms, atomic radius, coordination number and

atomic packing fraction for BCC and FCC structures. (10)

(iii) The distance between successive planes of Miller indices (111) i s 2.078ºA

for a metal having FCC structure. Find the atomic radius and volume of

its unit cell. (4)

OR

15. (b) (i) De¯ne the terms polymorphism and allotropy. (2)

(ii) Explain in detail the crystal defects and their types. (14)

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