Question

An initially non-polarized beam enters a vertical polarizer. The resulting beam then enters a second polarizer that is rotated 34.7 degrees from vertical.

What percent of the beam passes the second polarizer?

Answer 1

When a non polarised beam having intensity I1 pass through a polarizer P1 it is plane polarised. The resulting beam intensity I2 can be found using malus law. According to Malus law,

Since the polarizer P1 is vertical = 0. Therefore

This is 50% of initial beam intensity I1.

If this beam of intensity I2 again passes through a secong polariser P2 which is at an angle 34.7 degrees from vertical, the emerging beam intensity I3 can be found out again using Malus law. That is,

Substituting the value of we get,

Therefore only 33.79% of beam passes the secong polarizer.