Power and photons Example
How many photons are emitted every second from one watt of yellow light?
= Energy per photon * number of photons / time
= hf * n/sec; f?=c, so f = c/?
Power = (hc/?) * n/sec P = 1 Watt =
(6.63 x 10-34 J-s * 3 x 108 m/s / 5.5 x 10-7m) * n/sec;
n/sec = 2.8 x 1018 photons per second.