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  • A Laser light of wavelength 660 nm is used to weld Retina detachment.  If a Laser pulse of width 60 ms and power 0.5 kW is used the approximate number of photons in the pulse are : [Take Planck’s constant h=6.62×10−34

A Laser light of wavelength 660 nm is used to weld Retina detachment.  If a Laser pulse of width 60 ms and power 0.5 kW is used the approximate number of photons in the pulse are : [Take Planck’s constant h=6.62×10−34 Js]
Option: 1  1020
Option: 2 1018
Option: 3 1022
Option: 4 1019
 

Answers (1)

best_answer

As we discussed in

E= N \frac{hc}{\lambda }

or N=\frac{E\lambda }{hC}\:=\: \frac{0.5\times10^{3}\times60\times10^{-3}\times660\times10^{-9}}{6.62\times10^{-34}\times3\times10^{8}}

=\: \frac{10^{-8}\times6.60\times10^{2}}{6.62\times10^{-26}}=10^{20}

 

Posted by

vishal kumar

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