A linearly polarized monochromatic light of intensity \(10\) lumen is incident on a polarizer. The angle between the direction of polarization of the light and that of the polarizer such that the intensity of output light is \(2.5\) lumen is:

A monochromatic light of frequency \(500\) THz is incident on the slits of a Young's double slit experiment. If the distance between the slits is \(0.2\) mm and the screen is placed at a distance \(1\) m from the slits, the width of \(10\) fringes will be:
1. \(1.5\) mm
2. \(15\) mm
3. \(30\) mm
4. \(3\) mm

In Young's double-slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes:

1.  half

2.  four times

3.  one-fourth

4.  double 

The Brewster's angle for an interface should be:

1. 30° < ${\mathrm{i}}_{\mathrm{b}}$ <45°

2. 45° < ${\mathrm{i}}_{\mathrm{b}}$ < 90°

3. ${\mathrm{i}}_{\mathrm{b}}$ = 90°

4. 0° < ${\mathrm{i}}_{\mathrm{b}}$ < 30°

Two coherent sources of light interfere and produce fringe patterns on a screen. For the central maximum, the phase difference between the two waves will be: 

1.  zero 

2.  $\pi$

3.  $3\pi /2$

4.  $\pi /2$

In a double-slit experiment, when the light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed 1 m away, was found to be 0.2$°$. What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? $\left({\mu }_{water}=4/3\right)$

1. 0.1$°$

2. 0.266$°$

3. 0.15$°$

4. 0.05$°$