Question

An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30° in clockwise direction, the intensity of emerging light will be ________ Lumens.

Hint:

Malus' Law ($I = I_0 \cos^2 \theta$) applies to the intensity of light after it passes through a second polarizing filter (the analyzer).

Answer 1

Correct Answer: 75

Step 1: Let the initial intensity emerging from the analyzer be $I_0 = 100$ Lumens. This occurs when the polarizer and analyzer are presumably aligned ($\theta = 0^\circ$).
Step 2: According to Malus' Law, the intensity of transmitted light is $I = I_{max} \cos^2 \theta$.
Step 3: Here, $\theta = 30^\circ$.
Step 4: $I = 100 \times \cos^2(30^\circ) = 100 \times (\frac{\sqrt{3}}{2})^2 = 100 \times \frac{3}{4} = 75$ Lumens.