Question

Monochromatic light of frequency `6.0 xx 10^(14) Hz` is produced by a laser. The power emitted is `2 xx 10^(-3)` w. The number of photons emitted, on the average, by the sources per second is
A. `5xx10^(16)`
B. `5xx10^(16)`
C. `5xx10^(17)`
D. `5xx10^(14)`

Answer 1

Correct Answer - A
Powerr emitted, `P=2xx10^(-3)W`
Energy of photon, `E=hv=6.6xx10^(-34)xx6xx10^(14)J`
Number of photons emitted per second
`n=(P)/(E)=(2xx10^(-3))/(6.6xx10^(-34)xx6xx10^(14))`
`=5xx10^(-15)`.