1.

An unpolarised beam of light is incident on a group of four polarising sheets which are arranged in such a way that the characteristic direction of each polarising sheet makes an angle of 30^(@) with the preceding sheet. What fraction of light is transmitted?

Answer»

`(27)/(54)`
`(27)/(81)`
`(27)/(128)`
`(27)/(112)`

SOLUTION :Here `I_(1) = (I_(0))/(2), I_(2) = I_(1) cos^(2) 30^(@)`
`I_(3) = I_(2)cos^(2)30^(@)` and `I_(4) = I_(3)cos^(2)30^(@)`
`therefore I = (I_(0))/(2)(cos^(2)30^(@))^(3) = (I_(0))/(2) = (I_(0))/(2) cos^(6)30^(@)`
`therefore (I)/(I_(0)) = (27)/(128)`


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