Wave Optics

Two coherent monochromatic light beams of intensities 4I and 9I are superimposed. The difference between the maximum and minimum intensities in the resulting interference pattern is xI. The value of x is .

Two monochromatic light beams have intensities in the ratio 1:9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is

1. 8 : 1
2. 4 : 1
3. 3 : 1
4. 9 : 1

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.

The Young's double slit interference experiment is performed using light consisting of 480 nm and 600 nm wavelengths to form interference patterns. The least number of the bright fringes of 480 nm light that are required for the first coincidence with the bright fringes formed by 600 nm light is

1. 8
2. 4
3. 5
4. 6

In a Young's double slit experiment, three polarizers are kept as shown in the figure. The transmission axes of P1 and P2 are orthogonal to each other. The polarizer P3 covers both the slits with its transmission axis at 45 to those of P1 and P2. An unpolarized light of wavelength and intensity I0 is incident on P1 and P2. The intensity at a point after P3 where the path difference between the light waves from s1 and s2 is 3, is [figure]

1. I0
2. I03
3. I04
4. I02

Young's double slit interference apparatus is immersed in a liquid of refractive index 1.44. It has slit separation of 1.5 mm. The slits are illuminated by a parallel beam of light whose wavelength in air is 690 nm. The fringe-width on a screen placed behind the plane of slits at a distance of 0.72 m, will be:

1. 0.63 mm
2. 0.33 mm
3. 0.46 mm
4. 0.23 mm