When one polarizer is placed perpendicularly to an incident

When one polarizer is placed perpendicularly to an incident light and then rotated by one full cycle (360 degree), the ratio between the measured maximum and minimum transmitted light intensity is 5. What is the degree of polarization of the incident light?

Solution

Say, there were 100 units of light intensities, out of which p units were polarized and (100-p) unpolarized.

The maximum intensity will be obtained when the polarizer be at the same angle as the polarisation of light:--

In this case the intensity will be : max_Inetnsity = p + (100-p) =100

The minimum intensity will be obtained when the polarizer be at the ninty degree angle as the polarisation of light:--

In this case the intensity will be : min_Inetnsity = (100-p)

according to the prob:

max_Inetnsity = 5 x min_Inetnsity ==> 100 = 5 x (100-p) ==> p = 80

==> 80% is the degree of polarization