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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 ?

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We assume the Sun to be a blackbody. Then the wave-length of maximum emission and the surface temperature are related by Wien.s law.
Calculation `:` Given `: lambda_("max") = 0.5 mu m = 5 xx 10^(-3) mK`
Then from Wien.s law, we known that the product of the wavelength for maximum power emission is
`lambda_("max") T = 2.898 xx 10^(-3) mK`
We can solve for the temperature since we known `lambda_("max")`
` T = ( 2.898 xx 10^(-3) mK )/( 5 xx 10^(-7) m)`
= 6000 K
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RESNICK AND HALLIDAY-HEAT-MEASUREMENT AND TRANSFER-SOLVED PROBLEM 19.07
  1. What is the approximate radius of the central bright differaction spot...

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