A unpolarised light is passed through 3 polarisers. If the second polariser is at an angle `30^(@)` with the first and the third polariser is at an angle `60^(@)` with the second. Find the final intensity of the light passed through this combination in initial intensity was I.

Explanation

After passing through first polarizer `I=(I_(o))/(2)`
After second polarizer `I=(I_(0))/(2)cos ^(2)(30^(@))=3/8I_(0)`
After third polarizer `I=(3I_(0))/(8)cos ^(2)(60^(@))=(3I_(0))/(32)`
So final intensity `=(3I_(0))/(32)`