In Young’s double-slit experiment, the slits are separated by \(0.28~\text{mm}\) and the screen is placed \(1.4 ~\text m\) away. The distance between the central bright fringe and the fourth bright fringe is measured to be \(1.2~\text{cm}.\) The wavelength of light used in the experiment is:
1. \(600~\text{nm}\)
2. \(500~\text{nm}\)
3. \(400~\text{nm}\)
4. \(200~\text{nm}\)

In Young’s double-slit experiment using monochromatic light of wavelength \(\lambda,\) the intensity of light at a point on the screen where path difference \(\lambda\) is \(K\) units. What is the intensity of the light at a point where path difference is \(\lambda/3\)?
1. \(\dfrac K3\)
2. \(\dfrac K4\)
3. \(\dfrac K2\)
4. \(K\)

In a double-slit experiment the angular width of a fringe is found to be \(0.2^\circ\) on a screen placed \(1 ~\text{m}\) away. The wavelength of light used is \(600 ~\text{nm}.\) What will be the angular width of the fringe if the entire experimental apparatus is immersed in water?
(Take the refractive index of water to be \(4/3\)).
1. \(0.33^\circ\)
2. \(0.20^\circ\)
3. \(0.15^\circ\)
4. \(0.10^\circ\)

What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5.)

1. $49.{29}^0$
2. $43.{21}^0$
3. $50.{30}^0$
4. $56.{31}^0$

What is the distance for which ray optics is a good approximation for an aperture of 4 mm and wavelength 400 nm?

1. 40 m
2. 30 m
3. 20 m
4. 50 m

When the light diverges from a point source, the shape of the wavefront is:
1. Parabolic
2. Plane
3. Spherical
4. Elliptical

When the light is coming from a distant star that is intercepted by the earth, the shape of the wavefront is:

The refractive index of glass is \(1.5\). What is the speed of light in glass? 
1. \(2 \times 10^{8}~\text{m/s}\)
2. \(3 \times 10^{8} ~\text{m/s}\)
3. \(1.5 \times 10^{8} ~\text{m/s}\)
4. \(2.2 \times 10^{8}~\text{m/s}\)

Which of the following is not true?

A beam of light consisting of two wavelengths \(650~\text{nm},\) and \(520~\text{nm},\) is used to obtain interference fringes in Young’s double-slit experiment. What is the distance of the third bright fringe on the screen from the central maximum for wavelength \(650~\text{nm}?\)