A completely unpolarized light of intensity I0 is incident on a polarizer, then the emergent ray passes through an analyzer. The intensity of final emergent ray is I08. If analyzer is rotated about its own geometrical axis through an angle of 90o, intensity of final emergent ray will be

Intensity of light emerging from the polarizer is I02 and this light is plane polarized. If an angle between the axis of transformation of polarizer and that of analyzer is θ, then intensity of light coming out is I=I02cos2θ=I08⇒θ=60oAfter the analyzer is rotated, intensity of final emergent light is given byI=I02cos2π2±θ=I02cos290o±60o=3I08