PREVIOUS YEAR QUESTIONS-MODULE-3-ASSIGNMENT-3

Sree Narayana Guru College of Engineering and Technology, Payyanur
Third Assignment 2007-2008
EN2K6 102: ENGINEERING PHYSICS
Answer any 10 of the following questions

1.Explain metastable state and optical pumping. (2004)
2.Mention the characteristics of a laser beam and any two applications. (2004)
3.Explain the construction and working of a ruby laser with energy level diagram. (2004,2006)
4.A ruby laser emits pulses of 20 ns duration with average/pulse being 0.1 MW. If the number of photons in each pulse is 6.981Χ 1015,calculate the wavelength of photons. (2004)
5.What are the requisities for laser action. (2005)
6.With the energy level diagram explain the construction and working of He-Ne laser. (2005)
7.Find the ratio of the two energy states of the ruby laser, the transition between which is responsible for the emission of photons of wavelength 694.3 nm. Assume the ambient temperature as 270C, Boltzmann constant k = 1.38 Χ 10-23 J/K and Planck’s constant h = 6.63 Χ 10-34 Js (2005)
8.Explain the terms spontaneous emission and optical pumping. (2006)
9.Explain stimulated emission and population inversion. (2006)
10.Calculate the energy difference in eV between the two energy levels of the neon atoms of a He-Ne laser, the transition between which results in the the emission of light of wavelength 632.8 nm. Also estimate the number of photons emitted/sec if the optical output is 1 mw. (2006)
11.Explain in brief the principle of holography. (2005)
12.Discuss the signal distortion in optical fibres. (2004,2006)
13.Explain with block diagram point to point communication in optical fibres. (2004)
14.Calculate the numerical aperture and angle of acceptance for an optical fibre having refractive indices 1.563 and 1.498 for the core and cladding respectively. (2004)
15.Mention any five advantages of optical fibre. (2005)
16.With theory explain how light is propagated through an optical fibre. (2005)
17.Obtain an expression for numerical aperture and explain briefly point to point communication using optical fibres. (2006)
18. What are ultrasonics? What are their properties? (2006)
19. Write a note on nondestructive testing by ultrasonic method. (2004)
20. Write a note on radiographic method of nondestructive testing. (2005)
21. Describe the procedure of nondestructive testing by electrical method. (2006)

LAST DATE FOR SUBMISSION: 28-03-2008