Mahatma Gandhi University BSc Physics www.mgu.ac.in : Model Question Paper

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Model Question Paper
Model I, Model II and Model III
MAHATMA GANDHI UNIVERSIY
V SEMESTER B.Sc PHYSICS EXAMINIATION 20…
PH5B02U PHYSICAL OPTICS AND PHOTONICS

MGU Physics Question List : http://mgu.ac.in/index.php?option=co...article&id=894
MGU Question Page : http://www.mgu.ac.in/files/PH5B02U%20Physical%20Optics%20and%20Photonics(1).pdf

Instructions:
1. Time allotted for the examination is three hours
2. Answer all questions in part-A. This contains 4 bunches of 4 objective type questions. For each bunch, Grade A will be awarded if all the 4 answers are correct, B for 3, C for 2, D for 1 and E for 0.Answer any 5 questions from part B, any 4 from part C and any 2 from part D
3. Candidates can use non programmable scientific calculator

Part A (Objective type-weight 1 each)
Bunch I
Choose the correct answer.
1. If white light is used instead of monochromatic light to form Newton’s rings due to reflected light, the center will be
(a) dark (b) bright (c) colored (d) uniform illumination throughout

2.In a zone plate,
(a) the radii of the zones are proportional to squares of natural numbers.
(b) the even numbered zones are transparent.
(c) the odd numbered zones are opaque to light
(d) the radii of the zones are proportional to square root of natural numbers.

3. In double refraction
(a) o-ray and e- ray travels with different velocity along the optic axis.
(b) the velocity of the e- ray is maximum along the optic axis in positive crystals.
(c) the o-ray travels slower than e-ray in all directions except along the optic axis.
(d) the principal refractive index for o-ray is larger than the principal refractive index for e-ray in positive crystals.

4. If n1 is the refractive index of core n2 is the refractive index of cladding, the numerical aperture is given by
(a) n1 + n2 (b) n1 - n2 (c) ( n1 - n2 )2 (d) (n1 2 - n2 2 )1/2

Bunch II
Fill in the blanks.
5. The condition for darkness of a thin film in reflected light is ----------
6. In the case of Fraunhoffer diffraction the wave front in incident on the aperture is
7. A quarter wave plate introduces a phase difference of ------------
8. The role of an optical resonator in a laser system is to provide --------------

Bunch III
Write true or false; if false correct it
9. Two independent sources of light having same wave length can never be coherent.
10. The intensity of image form by a zone plate is more than that formed by a convex lens.
11. In positive crystals the e-ray velocity has a maximum value along the optic axis and a minimum value in a direction perpendicular to the optic axis.
12. Continuous wave laser operation is possible only in a three level pumping scheme