B.E./B.Tech. DEGREE EXAMINATION, JUNE 2011.
Common to all B.E./B.Tech.
182101 — ENGINEERING PHYSICS — I
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A — (10 ´ 2 = 20 marks)
1. State any two properties of ultrasonic waves.
2. An ultrasonic source of .07 MHz sends down a pulse towards the seabed which
returns after 0.65 sec. The velocity of sound in seawater is 1700 m/s. Calculate
the depth of the sea.
3. What are the characteristics of LASER?
4. Give the wavelengths of light emitted by the CO2 laser.
5. Define attenuation in an optical fibre and mention its unit.
6. Calculate the numerical aperture and acceptance angle of an optical fibre
having 1.49 1 n = and 1.44 2 n = .
7. State Wien's displacement law of black body radiation.
8. Mention any two limitations of Transmission Electron Microscope (TEM).
9. What are Miller indices?
10. Define Polymorphism and allotrophy.
PART B — (5 ´ 16 = 80 marks)
11. (a) (i) How will you produce ultrasonic waves using piezo electric
(ii) A quartz crystal of thickness .005 m is vibrating at resonance.
Calculate the fundamental and first overtone frequency, given the
Young's modulus for quartz as 7.9 ´ 1010 N/m2 and density of quartz
2650 kg/m3. (4)
(b) Describe the following :
(i) Industrial applications of ultrasonics. (8)
(ii) Different modes of scanning used in ultrasonic imaging technique.
12. (a) (i) Derive expressions for the Einstein's coefficient of spontaneous and
stimulated emissions. (8)
(ii) Explain the construction and working of He-Ne laser. (8)
(b) (i) Describe the construction and working of homo-junction and
hetero- junction semiconductor lasers. (10)
(ii) Define holography. Explain the working principle of construction of
a hologram with a neat sketch. What are its applications? (6)
13. (a) (i) Obtain expressions for numerical aperture and acceptance angle of
an optical fibre. (8)
(ii) Describe the double crucible technique of the production of fibre
(b) (i) Write short notes on temperature and displacement sensors. (8)
(ii) Describe the optical fibre communication with a neat block
14. (a) Write down the Schrodinger's wave equation for a particle in a box. Solve
it to obtain eigen function and show that eigen values are discrete. (16)
(b) (i) Explain the working of Scanning Electron Microscope with neat
(ii) Calculate the de Broglie wavelength of a proton whose kinetic
energy is 1 MeV. (4)
15. (a) Show that the packing density of Hexogonal Closed Packed (HCP) system
is the same as that of Face Centered Cubic (FCC) system. (16)
(b) (i) Obtain the number of atoms per unit cell, the coordination number,
atomic radius and the packing density of Body Centered Cubic
(BCC) system. (8)
(ii) Write short notes on point defects. (8)