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Monochromatic light of frequency 6.0xx10...

Monochromatic light of frequency `6.0xx10^(14)Hz` is produced by a laser. The power emitted is `2.0xx10^(-3)`W. (a). What is the energy of a photon in the light beam? (b) How many photons per second, on an average are emitted by the source?

Text Solution

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(i) Energy of each photon,
`E = h upsilon = 6.6 xx 10^(-34) xx 6 xx 10^(14)`
`E = 3.98 xx 10^(-19)J`
(ii) If N is the number of photons emitted per second by the source, then
Power transmitted in the beam `= N xx` energy of each photon
P = NE
`N = (P)/(E) = (2 xx 10^(-3))/(3.98 xx 10^(-19))`
`N = 5 xx 10^(15)` photons per second
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