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A plane wave front of light is incident ...


A plane wave front of light is incident on a plane mirror. Intensity is maximum at P when

A

`costheta=(lamda)/(2d)`

B

`costheta=(3lamda)/(4d)`

C

`sectheta-costheta=(3lamda)/(4d)`

D

`sectheta-costheta=(lamda)/(2d)`

Text Solution

Verified by Experts

The correct Answer is:
B

`BP=(MP)/(costheta)`
`AB=BPcos2theta=(MP)/(costheta)cos2theta`
`AB+BP=nlamda+(lamda)/(2)`
`(d cos2theta)/(costheta)+(d)/(costheta)=(d)/(costheta)(2cos^(2)theta-1+1)=2dcostheta=nlamda+(lamda)/(2)` for `n=1,costheta=(3lamda)/(4d)`
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