An unpolarized beam of light of intensity passes through two linear polarizers making an
angle of 30$°$ with respect to each other. The emergent beam will have an intensity:

1.  $\frac{3{\mathrm{l}}_0}{4}$

2.  $\frac{\sqrt{3}{\mathrm{l}}_0}{4}$

3.  $\frac{3{\mathrm{l}}_0}{8}$

4.  $\frac{{\mathrm{l}}_0}{8}$

A beam of monoenergetic electrons, which have been accelerated from rest by a potential U, is used to form an interference pattern in Young's double-slit experiment. The electrons are now accelerated by potential 4U. The fringe width:

1.  Remains the same

2.  Is half the original fringe width

3.  Is twice the original fringe width

4.  Is one-fourth the original fringe width

A source of light $\left(f = 6.0 \times {10}^{14} Hz \right)$ passes through three planes polarizes. The first two polarizers are in the same direction, while the third is rotated $90°$ with respect to the second polarizer. What is the frequency of the light that comes out of the third polarizer?

1.  $3.0 \times {10}^{14} Hz$

2.  $6.0 \times {10}^{14} Hz$

3.  $9.0 \times {10}^{14} Hz$

4.  Light will not pass through the third polarizer

In young's experiment, the wavelength of red light is $7.8\times {10}^{-5}$ cm and that of blue light $5.2\times {10}^{-5}$ cm. The value of n for which (n+1)th blue bright band coincides with the nth red band is:

1. 4

2. 3

3. 2

4. 1

Light of wavelength 6000 $\stackrel{0}{A}$ is incident on a single slit. The first minimum of the diffraction pattern is obtained at 4 mm from the center. The screen is at a distance of 2 m from the slit. The slit width will be:

1. 0.3 mm

2. 0.2 mm

3. 0.15 mm

4. 0.1 mm

In Young's double-slit experiment, the distance between the two sources is 0.1 mm. The distance of the screen from the sources is 20 cm. The wavelength of light used is 5460 $\stackrel{0}{A}$. Then the angular position of first dark fringe is:

1. 0.08$°$

2. 0.16$°$

3. 0.20$°$

4. 0.32$°$

The main difference between the phenomena of interference and diffraction is that:

In Young's double-slit experiment, the phase difference  between light waves reaching 3rd bright fringe from the central fringe when $\lambda =5000 \stackrel{0}{A}$, is:

1. $6\pi$

2. $2\pi$

3. $4\pi$

4. zero

In an interference pattern produced by two identical slits, the intensity at the position of the central maximum is \(I.\) The intensity at the same spot when either of the slits is closed is \(I_0.\) Therefore,
1. \(I=I_0\)
2. \(I=2I_0\)
3. \(I=4I_0\)
4. \(I\) and \(I_0\) are not related to each other

The separation between successive fringes in a double-slit arrangement is x. If the whole arrangement is dipped underwater, what will be the new fringe separation? [The wavelength of light being used is 5000 $\stackrel{0}{A}$]

1. 1.5 x

2. x

3. 0.75 x

4. 2 x