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(a) Using the phenomenon of polarisation, show how transverse nature of light can be demonstrated. (b) Two polaroids P_(1) and P_(2) are placed with their pass axes perpendicular to each other. Unpolarised light of intensity I_(0) is incident on P_(1). a third polaroid P_(3) is kept in between P_(1) and P_(2) such that its pass axis makes an angle of 30^(@) with that of P_(1). determine the intensity of light transmitted through P_(1),P_(2) and P_(3). |
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Answer» Solution :(b) When unpolarised light of intensity `I_(0)` is incident on polaroid `P_(1)`, the intensity of plane polarised transmitted light: `I_(1)=(I_(0))/(2)` As PASS axis of polaroid `P_(3)` makes an angle of `30^(@)` with that of `P_(1)`, the intensity of light transmitted through `P_(3)` is `I_(2)=I_(1)cos^(2)(30^(@))=(I_(0))/(2)xx((sqrt(3))/(2))^(2)=(3I_(0))/(8)` Further the polaroid `P_(2)` is PLACED with its pass axis perpendicular to that of `P_(1)`, hence `P_(2)` is INCLINED an angle `90^(@)-30^(@)=60^(@)` with `P_(3)`. hence, the intensity of light transmitted through `P_(2)` is `I_(3)=I_(2)cos^(2)(60^(@))=(3I_(0))/(8)xx((1)/(2))^(2)=(3I_(0))/(32)`. |
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