Intensity of Polarised Light

Q.

A polarizer-analyzer set is adjusted such that the intensity of light coming out of the analyzer is just $10\%$ of the original intensity. Assuming that the polarizer-analyzer set does not absorb any light, the angle by which the analyzer need to be rotated further to reduce the output intensity to be zero is

1. $45°$

2. $90°$

3. $71.6°$

4. $18.4°$

Q.

A flood light is covered with a filter that transmits red light. The electric field of the emerging beam is represented by a sinusoidal plane wave $E_x=36\sin (1.20\times {10}^{7}z+6\times {10}^{15}t)V/m$. The average intensity of the beam will be

Q.

The amplitude of the electric field in a parallel beam of light of intensity $4·0W{m}^{-2}$ is __________.

1. $54·87N{C}^{-1}$

2. $19·4N{C}^{-1}$

3. $9·76N{C}^{-1}$

4. None of these

Q. Intensity of unpolarised light incident on a polarizer is $2a^2$ then amplitude of emergent ray (Assuming zero absorption in the Polaroid)

1. $\frac{a}{2}$
2. a
3. $\frac{\sqrt{3}a}{2}$
4. $\frac{3a}{4}$

Q.

A Carnot engine whose sink is at $300K$ has an efficiency of $40\%$. By how much should the temperature of the source be increased so as to increase its efficiency by $50\%$ of original efficiency?

1. $380K$

2. $275K$

3. $215K$

4. $250K$

Q. A polarizer-analyzer set is adjusted such that the intensity of light coming out of the analyzer is just $10\%$ of the original intensity. Assuming that the polarizer-analyzer set does not absorb any light, the angle by which the analyser need to be rotated further to reduce the output intensity to be zero is

1. ${45}^o$
2. ${71.6}^o$
3. ${90}^o$
4. ${18.4}^0$

Q. Unpolarized light with an intensity of $I_0=16\frac{W}{m^2}$ is incident on a pair of polarizers. The first polarizer has its transmission axis aligned at ${50}^{\circ }$ from the vertical. The second polarizer has its transmission axis aligned at ${20}^{\circ }$ from the vertical.

What is the intensity of the light when it emerges from the second polarizer?

1. $4\frac{W}{m^2}$
2. $8{\cos }^2{20}^{\circ }\frac{W}{m^2}$
3. $6\frac{W}{m^2}$
4. $12\frac{W}{m^2}$

Q. Unpolarized light of intensity I passes through an ideal polariser A. Another identical polarizer $B$ is placed behind $A$. The intensity of light beyond B is found to be $\frac{I}{2}$. Now another identical polarizer $C$ is placed between A and B. The intensity beyond $B$ is now found to be $\frac{I}{8}$. The angle between polarizer $A$ and $C$ is :

1. $0^{\circ }$
2. $0^{\circ }$
3. ${45}^{\circ }$
4. ${60}^{\circ }$