At the end of Example 27.8, it was stated that the intensity of polarized light is reduced to 90.0% of its original value by passing through a polarizing filter with its axis at an angle of $18.4^\circ$ to the direction of polarization. Verify this statement.
This is College Physics Answers with Shaun Dychko. Some polarized light is going to be passing through a polarizing filter that has its axis of polarization at 18.4 degrees compared to the direction of polarization of the light and we are going to verify that the intensity that is after the polarization filter is 90 percent of what it was before the filter. So the intensity after passing through the filter is the original intensity before the filter times cos of this angle squared and so that is I naught times cos squared of 18.4 degrees which is 0.900 times I naught and that verifies that yes indeed the intensity after passing through the filter with this angle between the filter axis and the direction of polarization of the incident light is going to be 90 percent of what it was initially.