Unpolarised light of intensity 32 Wm−2 passes through three polarizers such that transmission axes of the first and second polarizer makes and angle 300 with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of final emerging light will be

Angle between P1 and P2=30∘ (given) Angle between P2 and P3=θ=90∘−30∘=60∘The intensity of light transmitted by P1 isI1=I02=322=16Wm2According to Malus law the intensity of light transmitted by P2 isI2=I1cos230∘=16322=12Wm2Similarly intensity of light transmitted by P3 isI3=I2cos2θ=12cos260∘=12122=3Wm2