B.E./B.Tech. DEGREE EXAMINATION, JANUARY 2011.
Common to all branches
182101 – ENGINEERING PHYSICS – I
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A — (10 × 2 = 20 marks)
1. Can we use a copper rod in a magnetostriction generator? Why?
2. An ultrasound pulse sent by a source in sea is reflected by a submerged target
at a distance 597.50m and reaches the source after 0.83 seconds. Find the
velocity of sound in sea water.
3. Can a two-level system be used for the production of laser? Why?
4. Mention any two differences between a hologram and a photograph.
5. What is called mode of propagation in optical fibers?
6. Mention the properties of detectors used in fiber – optic communication.
7. Calculate the energy in eV of a photon of wavelength 1.2
A . (Planck's constant
= 6.62 × 10–34 Js. speed of light 3 10 m/ s 8 = × ).
8. Mention the physical significance of wave function of matter waves.
9. The interplanar distance of (110) planes in a BCC crystal is 2.03 A.
the lattice parameter of the crystal?
10. List the different types of point defects.
PART B — (5 × 16 = 80 marks)
11. (a) (i) Define piezoelectric effect. (2)
(ii) With a neat diagram, explain the construction and working of a
piezoelectric oscillator. (12)
(iii) Briefly outline the emulsification using ultrasonic waves. (2)
(b) (i) What is acoustic grating? With a neat diagram, explain the theory
and use of it to determine the ultrasonic velocity in a liquid. (2 + 8)
(ii) Briefly outline the various industrial applications of ultrasonic
12. (a) (i) With a neat diagram, explain the construction and working of a
2 CO laser. (12)
(ii) Outline the use of lasers in heat treatment. (4)
(b) (i) Explain the principle, construction and working of a semiconductor
diode laser with necessary diagrams. (12)
(ii) What are heterojunction lasers? Mention any two advantages of
them. (2 + 2)
13. (a) (i) Define the numerical aperture of an optical fiber. Derive an
expression for it. (2 + 8)
(ii) Explain the double crucible method of drawing optical fiber with
neat diagram. (6)
(b) (i) Discuss the mechanisms of attenuation, dispersion and bending
losses in optical fibers. (10)
(ii) Explain the principles of working of temperature and displacement
sensors using optical fibers. (6)
14. (a) Explain the theory of blackbody radiation due to Planck. Also discuss the
limits of high temperature and low temperature of the result. (10 + 6)
(b) (i) Derive the time-dependent (1–D) Schr&o&edinger equation from
(ii) Find the change in wavelength of an X-ray photon which is
scattered through an angle of 90o by an electron. (Planck's constant
= 6.62 × 10-34 Js; rest mass of electron = 9.1 × 10-31 kg; speed of light
= 3 × 108 m/s). (4)
15. (a) (i) Write the standard crystal systems corresponding to with their
lattice parameters. What are Bravias Lattices? (7)
(ii) Explain the procedure to obtain the Miller indices of crystal planes.
Also deduce a relation between Miller indices and the inter-planar
distance. (3 + 6)
(b) (i) The density of BCC iron is 7860 kg/m3 and its atomic weight is
55.85. Calculate its atomic radius. (6)
(Avogadro number = 6.023 × 1026/k mole)
(ii) Deduce the c/a ratio and packing factor of standard HCP crystal.