Question

Four ideal linear polarizers are placed in a row with the polarizing axis at angles 20°, 55°, 90° to the vertical. Natural light of intensity I_0 is incident on the first polarizer. What is the intensity of light emerging from the last polarizer?

A. I_0
B. I_0/2
C. I_0/4
D. I_0/8

Answer 1

The intensity of light emerging from the last polarizer is D.
`I_(0)`/8

When unpolarized light passes through a polarizer, its intensity is reduced to
`I_(0)`/2 because only the component of light parallel to the polarizing axis is transmitted.

Subsequent polarizers further reduce the intensity by a factor of 2 for each additional polarizer.

The reduction in intensity at each polarizer is proportional to
`(1)/(2)`, and with four polarizers, the final intensity is
`I_(0)`/
`2^(4)` =
`I_(0)`/8.

​

Therefore, the correct answer is D.