LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

           B.Sc. DEGREE EXAMINATION – PHYSICS

FG 10

THIRD SEMESTER – APRIL 2008

PH 3500 – OPTICS

 

 

 

Date : 26-04-08                  Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART A

Answer all questions:                                                                                                   (10 х 2 = 20)

1. Define unit planes.
2. State why crosswires cannot be used in Huygen’s eyepiece?
3. What are coherent sources?
4. In Newton’s rings experiment, the diameter of the 8^th ring changes from 1.4cm to 1.27cm

when a liquid is introduced between the lens and the plate. Calculate the refractive index

of the liquid.

5. Define resolving power of an optical instrument.
6. Compare a zone plate and a convex lens.
7. What is a half wave plate?
8. State the laws of optical activity.
9. What is meant by population inversion?
10. What is Raman effect?

PART B

Answer any FOUR  questions:                                                                                    (4 х 7.5=30)

1. a) Discuss with theory the construction of Ramsden eyepiece.                                             (4)

3. b) Find out the positions of its cardinal points. (3.5)

1. a) Describe with necessary theory the interference of light by a Lloyd’s mirror.                   (5)

2. b) In a Lloyd’s mirror experiment, the slit source is at a distance of 2.5 mm from

the mirror.  The screen is at a distance of 1.5m from the source.  Calculate the fringe width.

Wavelength of light is 5890 A.                                                                                               (2.5)

1. Discuss the missing orders in a double slit diffraction pattern.
2.  a) Describe the construction and working of a quarter wave plate.                                      (5)

1. b) Calculate the thickness of a half wave plate of quartz for a wavelength 5000A. Given

(2.5)

1. Describe the construction and working of a Ruby laser.

 

PART C

Answer any FOUR  questions:                                                                                   (4 х 12.5 = 50)

1. a) What is meant by chromatic aberration?                                                                             (2.5)

1. b) Show that chromatic aberration of a lens is equal to the product of the dispersive power

and the mean focal length of the lens.                                                                                                (5)

1. c) Deduce the condition for achromatism of two lenses separated by a distance. (5)

1. a) Give the theory of Newton’s rings.                                                                                                (7.5)

1. b) Describe an experiment to determine the wavelength of light using these rings. (5)

1. Describe and experiment to determine the wavelength of light using these rings.
2. a) What is polarization?                                                                                                          (2.5)

1. b) Explain the production and detection of (i) circularly and

(ii) elliptically polarised light.                         (5+5)

1. Explain the construction and working of a He-Ne laser.

 

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