Modern Physics Question?

Question

One of the parameters that is needed to determine the number of atoms trapped in a magneto-optical trap apparatus that is used to cool atoms is the number of photons per second incident on the cooled atoms. A beam in a magneto-optical trap is measured to have a power of 38.2 μW and the wavelength of the beam is 779 nm. How many photons per second are atoms exposed to when this beam is incident on them?

I can use the power and wavelength given to calculate for the number of photons, however I have no idea how the cooled atoms would factor into the problem. Would they affect the wave speed? If so how would I calculate the wave speed?

Answer 1

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The cooled atoms have nothing to do with the answer. If you've calculated photons per second (and remember that µW = µJ/s), then you're done.

photons/s = power (J/s) / energy per photon (J/photon)