Question

Light incident on a polarizer is then passed through a second polarizer. If the polarizer and the analyzer are perpendicular to each other, what
can you say about the light waves emerging from the second polarizer?
OA.
The light waves are partially blocked
OB.
The light waves are completely blocked.
OC.
The light waves are of the same intensity as the incident light.
OD.
The light waves have three times the intensity of the incident light.
OE
The light waves have half the intensity of the incident light.

Answer 1

Answer:

B. The light waves are completely blocked.

Explanation:

The intensity of the light coming out after two polarizers is given by Malus' Law:

$I=I_0 cos^2 \theta$

where

$I_0$ is the initial intensity of light before the polarizers

$I$ is the intensity of light after the two polarizers

$\theta$ is the angle between the axes of the two polarizers

In this problem, we have two polarizers with their axes placed perpendicular to each other: this means that the angle is 90 degrees

$\theta=90^{\circ}$

Therefore, the cosine factor is zero:

$cos 90^{\circ} = 0$

And this means that the intensity of light after the two polarizers is also zero:

$I=I_0 cos^2 90^{\circ} = I_0 \cdot 0 = 0$

So, the correct option is

B.  The light waves are completely blocked.