The Brewster's angle for an interface should be:
1. \(30^{\circ}<i_b<45^{\circ}\)
2. \(45^{\circ}<i_b<90^{\circ}\)
3. \(i_b=90^{\circ}\)
4. \(0^{\circ}<i_b<30^{\circ}\)

In Young’s double-slit experiment, the slit separation is doubled. To maintain the same fringe spacing on the screen, the screen-to-slit distance \(D\) must be changed to,
1. \(2~\text{D}\)
2. \(\frac{\text{D}}{2}\)
3. \(\sqrt{2}~\text{D}\)
4. \(\frac{\text{D}}{\sqrt{2}}\)

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. \(0.10^\circ\)

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. \(2.2 \times 10^{8}~\text{m/s}\)

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 \(650~\text{nm}?\)

A diffraction pattern is obtained by using a beam of red light. What will happen, if the red light is replaced by blue light?

1.  Bands will become narrower

2.  Bands become broader

3.  No change will take place

4.  Bands disappear

In Young's double slit experiment, a slit is covered with a thin film so that the optical path difference introduced between coherent waves is $5\lambda$. Then the new position of central maxima will be at

1.  The initial position of 5th maxima

2.  The initial position of 3rd minima

3.  The initial position of 2nd minima

4.  The initial position of 3rd maxima

The angular width of the central maximum in the Fraunhofer diffraction for \(\lambda=6000~{\mathring{A}}\) is \(\theta_0.\) When the same slit is illuminated by another monochromatic light, the angular width decreases by \(30\%.\) The wavelength of this light is:
1. \(1800~{\mathring{A}}\)
2. \(4200~{\mathring{A}}\)
3. \(420~{\mathring{A}}\)
4. \(6000~{\mathring{A}}\)

In Young's double-slit experiment, the intensity of light due to each slit is \(I_0.\) An interference pattern is observed on a screen \(S,\) placed parallel to the line joining the slits \(S_1\) and \(S_2.\)

                   
What are the values of minimum, maximum, and average intensities over the entire screen?
1. \(0, 4I_0, 2I_0\)
2. \(0, 4I_0, I_0\)
3. \(I_0, 2I_0, \dfrac{3I_0}{2}\)
4. \(0, 2I_0, I_0\)