Unpolarized light falls on an angle of 37.5 ° with a plan glass surface. The reflected light polarization is examined with a Polaroid. The ratio between maximum and minimum intensity from Polaroid when it is rotated around is 4.0. Which is the refractive of index glass? I would like to use the equation which relates the Intensity with the incident angles with the refraction angle. But doesn't really find out how.