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Number of photons that provide given energy

  1. Sep 14, 2008 #1
    How many photons of light having a wavelength of 656nm are necessary to provide 1J of energy?

    I know the equation E=hc/lambda, however I am unsure of what help calculating E would be. Do I just divide 1J by what E is?
  2. jcsd
  3. Sep 14, 2008 #2


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    Yes. Think in terms of units:

    E has units of energy per photon
    1J has units of energy

    So 1J / E has units of ________ ?
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