Problem 1
A glass chamber 25 mm filled with air is positioned infront of one the secondary sources in YDS setup. The air is removed from the chamber and a test gas is entered in its stead. On comparing the fringe system corresponding to air with the test gas, it is found that the entire interference pattern on the screen is displaced by
21 bright bands towards the side containing the chamber.

0
=656.2816 nm and n air
=1.000276. Determine the refractive index of the gas. [Answer: 1.000827]
Problem 2
Find the visibility of the fringes by YDS setup when two field amplitudes are equal. [Answer: 1]
Problem 3
A ray of green light (

0
=565.69 nm) impinges at 30 o on a thin planar film of index
1.500 immersed in air. (a) What is the smallest thickness for which the point of reflection appears on a maximum fringe? (b) What would that point look like if the film were 1500 nm thick? [Answer: 100 nm, bright]
Problem 4
Looking into a Michelson interferometer one sees a dark central disc surrounded by concentric bright and dark rings. One arm of the device is 2 cm longer than the other, and the wavelength of light is 500 nm. Determine (i) the order of the central disc and (ii) the order and angular position (
θp
) of the sixth (6th) dark ring from the center. [Answer: 80,000, 79994, 1.22x10
-2 rad]