posted by seema .
Unpolarized light with an average intensity of 750.0W.m^2 enters a polarizer with a vertical trasmission axis. the transmitted light then enters a second polarizer. the light that exits the second polarizer is found to have an average intensity of 125 W/m^2. what is the orintation angle of the second polarizer relative to the first one?
The actual angle depends upon the losses of the polarizers. For sheet Poloroid film, these losses are about 50% per sheet, in addition to the fraction that is lost due to polarization.
Only crystal prism polarizers (Nicol, Glan-Thompson, Wollaston etc.) are lossless. They are actually beam separaters, and are based on double refraction.
I will assume there are no losses in the preferred plane of polarization. Call the orientation angle theta. It is the rotation angle between the two preferred planes of polarization.
In your case, 1/6 of the light gets through the pair.
Cos(theta)^2 = 1/6
Cos theta = 0.408
theta = 66 degrees.