A beam of unpolarized light is incident on a glass surface at Brewster's angle. The reflected light is observed through a polaroid. Initially, the polaroid is oriented such that the transmitted intensity is zero. From this position, the polaroid is rotated by an angle . It is found that the transmitted intensity becomes one-third of the intensity blocked by the polaroid. The value of is:

Step-by-step solution

According to Brewster's Law, light reflected at Brewster's angle is completely plane-polarized. Let the intensity of this reflected light be I_ max . Initially, the transmitted intensity is zero, which means the pass axis of the polaroid is perpendicular to the plane of polarization of the reflected light (angle is 90^ ). When the polaroid is rotated by an angle from this initial position, the angle between its pass axis and the plane of polarization becomes (90^ - ) . By Malus's Law, the transmitted intensity I_t