Wave Optics

Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is:

1. 3 : 1
2. (2 2 + 1) : (2 2 - 1)
3. 9 : 1
4. (3 + 2 2) : (3 - 2 2)

A light wave is propagating with plane wave fronts of the type x + y + z = constant. The angle made by the direction of wave propagation with the x-axis is :

1. -1(2/3)
2. -1 ( 1 3 )
3. -1 ( 13 )
4. -1 ( 23 )

If the measured angular separation between the second minimum to the left of the central maximum and the third minimum to the right of the central maximum is 30 in a single slit diffraction pattern recorded using 628 nm light, then the width of the slit is .

A double slit interference experiment performed with a light of wavelength 600 nm forms an interference fringe pattern on a screen with 10th bright fringe having its centre at a distance of 10 mm from the central maximum. Distance of the centre of the same 10th bright fringe from the central maximum when the source of light is replaced by another source of wavelength 660 nm would be mm.

A thin transparent film with refractive index 1.4, is held on circular ring of radius 1.8 cm. The fluid in the film evaporates such that transmission through the film at wavelength 560 nm goes to a minimum every 12 seconds. Assuming that the film is flat on its two sides, the rate of evaporation is 10-13 m3/s.