Two polaroids are kept crossed to each other. Now one of them is rotated through an angle of $45°$. The percentage of incident light now transmitted through the system is:

1.  15%

2.  25%

3.  50%

4.  60%

A beam of light AO is incident on a glass slab (μ = 1.54) in a direction as shown in the figure. The reflected ray OB is passed through a Nicol prism. On viewing through a Nicole prism, we find on rotating the prism that:

Unpolarized light of intensity 32 Wm^–2 passes through three polarizers such that the transmission axes of the first and second polarizer make an angle of 30° with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of the final emerging light will be:

1. 32 Wm^–2

2. 3 Wm^–2

3. 8 Wm^–2

4. 4 Wm^–2

When an unpolarized light of intensity I₀ is incident on a polarizing sheet, the intensity of the light which does not get transmitted is:

1. Zero

2. I₀

3. $\frac{1}{2}{I}_0$

4. $\frac{1}{4}{I}_0$

On superposition of two waves \(y_{1}=3sin\left ( \omega t-kx \right )\) and \(y_{2}=4sin\left ( \omega t-kx+\frac{\pi }{2} \right )\) at a point, the amplitude of the resulting wave will be:

1.  7

2.  5

3.  $\sqrt{7}$

4.  6.5

In Young's double-slit experiment using the light of wavelength '$\lambda$', 60 fringes are seen on a screen. If the wavelength of light is decreased by 50%, then the number of fringes on the same screen will be:

1.  30

2.  60

3.  120

4.  90

If the polarising angle for a material is $60°$, then the refractive index of the material will be:

1.  $\frac{1}{\sqrt{3}}$

2.  $\frac{3}{2}$

3.  $\sqrt{3}$

4.  $\frac{\sqrt{3}}{2}$

Five identical polaroids are placed coaxially with \(45^{\circ}\) angular separation between pass axes of adjacent polaroids as shown in the figure. (I₀: Intensity of unpolarized light)
          
The intensity of light, I, emerging out of the 5^th polaroid is:

1.  $\frac{{\mathrm{I}}_0}{4}$

2.  $\frac{{\mathrm{I}}_0}{8}$

3.  $\frac{{\mathrm{I}}_0}{16}$

4.  $\frac{{\mathrm{I}}_0}{32}$

In Y.D.S.E., the ratio of maximum intensity at a point to the intensity at the same point when one slit is closed, is:

1. 2

2. 3

3. 4

4. 1

Two light sources are said to be coherent when their: