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Quantum of light

  1. Oct 31, 2012 #1
    I am confused. Hot many photons are to each wave of light? Is there only one, like I thought, or are there many?
  2. jcsd
  3. Nov 1, 2012 #2
    That's a tricky question - what exactly is "one wave of light"?
    Each photon carries an energy of hf (f=frequency), so if you have light of a certain wavelength with a well-defined amount of energy, it is easy to find out how many photons it carries.
    However, if you have coherent light (like that emitted from a laser), it does not have a definite number of photons in it - coherent light has to exist in a superposition state of different photon numbers; otherwise it could not be coherent.
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