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Homework Help: Photon Question-Energy Quantization Question-please help!

  1. Oct 16, 2007 #1
    Photon Question-Energy Quantization Question---please help!

    This is a somewhat simple question I'm just unsure what relations to use. I found an equation relating number of protons to power and frequency but i'm not sure how to apply it to this case.

    EQUATION?

    Power = energy per unit time
    = (energy per photon) * (photon per unit time)
    = (h*f) * (photons per unit time)

    *where*
    Power = wattage
    h = Planck's constant
    f = frequency.


    QUESTION
    A certain laser outputs pure red light (photon energy 1.8 eV) with power 550 milliwatts (0.55 watts). How many photons per second does this laser emit?
    photons/s

    -Thanks!!
     
  2. jcsd
  3. Oct 16, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Looks like you have the correct relations. Just be sure to convert everything to standard units: eV to Joules, mW to Watts.
     
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