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Monochromatic light of frequency 6.0xx10^(14) Hz is produced by a laser. The power emitted is 2.0 xx10^(-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? |
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Answer» SOLUTION :(a) Each photon has an energy `E=hv=(6.63xx10^(-34)Js)(6.0xx10^(14Hz))` `=3.98xx10^(-19)J` If N is the number of PHOTONS emitted by the source per second, the POWER P transmitted in the beam EQUALS N times the energy per photon E, so that P = N E. Then `N=(P)/(E)=(2.0xx10^(-3)W)/(3.98xx10^(-19)J)` `=5.0xx10^(15)" photons per second."` |
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