Plane polarized light is sent through two consecutive polarizers,the first having its plane of polarization in the same direction as the incident light and the second having its plane at 90° to the original plane of polarization.A third polarizer,with plane of polarization at 21.6° to the original plane of polarization,is placed between the two other polarizers.What fraction of the original intensity now gets through?
A) 0
B) 0.432
C) 0.747
D) 0.059
E) 0.232

Question

Plane polarized light is sent through two consecutive polarizers,the first having its plane of polarization in the same direction as the incident light and the second having its plane at 90° to the original plane of polarization.A third polarizer,with plane of polarization at 21.6° to the original plane of polarization,is placed between the two other polarizers.What fraction of the original intensity now gets through?
A) 0
B) 0.432
C) 0.747
D) 0.059
E) ​0.232

Quizplus · Accepted Answer

When the third polarizer is added at 21.6°, the intensity after the first polarizer is unchanged. The intensity after the third polarizer is I*cos²(21.6°), and after the second polarizer, it is I*cos²(21.6°)*cos²(68.4°). Calculating this gives approximately 0.059.

Plane Polarized Light Is Sent Through Two Consecutive Polarizers,the First