Two nicols are so oriented that the maximum amount of light is transmitted. To what fraction of its maximum value is the intensity of transmitted light reduced when the analyser is rotated through (i) `45^(@)` (ii) `90^(@)` (iii) `180^(@)`. ?

Explanation

As `I = I_0 cos^2 theta`
(i) `I = I_0 cos^2 theta`
(i) `I = I_0 cos^2 45^@ = (I_0)/2 = 50%`
(ii) `I = I_0 cos^2 90^@ = 0`
(iii) `I = I_0 cos^2 180^@ = I_0(-1)^2 = -I_0 = 100%`.