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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» <P> Solution :(a) Light from the sodium LAMP passing through the single POLAROID sheet `(P_(1))` does not show any variation in INTENSITY when this sheet is rotated. However, if the light transmitted by `P_(1)`, is made to pass through another polaraied sheet `(P_(2))`, the light intensity coming out of `P_(2)`, varies from a maximum to zero, and again to maximum, when `P_(2)` is rotated. These observations are consistent only with the transverse nature of light waves. `(b)` Intensity of light transmitted through `P_(1)=(I_(0))/(2)` Intensitiy of light transmitted through `P_(3)=((I_(0))/(2))xxcos^(2)30^(@)` `=(3I_(0))/(8)` Intensity of light transmitted through `P_(2)=P_(3)xxcos^(2)(90^(@)-30^(@))=(3)/(8)I_(0)cos^(2)60^(@)` `=(3)/(32)I_(0)` |
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