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What is the approximate radius of the ce...

What is the approximate radius of the central bright differaction spot of light of wavelength `lambda=0.5 mum`, if focal length of the lens is 20 cm and radius of aperture of the lens is 5 cm ?

Text Solution

Verified by Experts

`r_(0)~~(0.61 lambdaf)/a`
Putting values
`r_(0)=(0.61xx0.5xx10^(-6)xx20xx10^(-2))/(5xx10^(-2))=1.22xx10^(-6)m=1.22 mum`
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