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How many photons are emitted by a laser ...

How many photons are emitted by a laser source of `5 xx 10^(-3)` W operating at 632.2 nm in 2 second `(h = 6.63 xx 10^(-34)Js)`?

A

`3.2 xx 10^(16)`

B

`1.6 xx 10^(16)`

C

`4 xx 10^(16)`

D

None of these

Text Solution

Verified by Experts

The correct Answer is:
A
Energy of each photon
`E_(0)=(hc)/(lambda)=(6.63xx10^(-34)xx3xx10^(8))/(632.2 xx 10^(-9))=3.15 xx 10^(-19)J`
Total energy = E = Pt
`therefore" "nE_(0)=Pt`
`therefore " "n=(Pt)/(E_(0))=(5xx10^(-3)xx2)/(3.15xx10^(-19))=3.2xx10^(16)`
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