Given Watts and Herzt of an electromagnetic wave, how do I calculate photons per second?

Question

I hate being that person posting homework question but my textbook is a joke and I can't figure it out.

Answer 1

The energy of a photon is

E = hf

where h is Planck's Constant and f the frequency.

Power is work (or energy) divided by time.

The power tells you how many Joules you have per second. The equation above gives you the number of Joules per photon. So divide the work by the energy per photon to get the number of photons per second.