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Frequency of a photon

  1. Feb 24, 2014 #1
    When we say the frequency of electromagnetic radiation, how can we conceptualize this property's manifestation in photons?

    Are the photons oscillating in space with the corresponding frequency? If yes, would this oscillation be parallel, perpendicular, or something else with respect to the direction of propagation, and what would determine its amplitude?

    I suppose this question could apply to any particle. Thank you for your time!
  2. jcsd
  3. Feb 24, 2014 #2

    Simon Bridge

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    It is generally a bad idea. What we do instead is use the concept to work out properties of the radiation. The properties we care about depend on how we look at it.

    Photon frequency should be thought of as energy and momentum, since photons belong to the particle model. It's just handy to use frequency for it's links with classical electromagnetism.

    The photon is not usefully thought of as a little vibrating ball of anything.

    The "frequency of a photon" is a quantum mechanical property that is analogous to the frequency in electromagnetic waves. In that case, it is the time rate of change of the magnitude of the electric field. How would you "conceptualize" the electric field? But the electromagnetic field stuff is what you get from lots of photons.

    See also: photoelectric effect.
  4. Feb 24, 2014 #3


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    Frequency (f) determines the quantum of energy per Planck's relation: E = h*f .

    Also wavelength * frequency = c, the speed of light. The wavelength (lambda) determines the magnitude of the momentum per de Broglie's relation: p = h/lambda.

    So if your laser emits light with wavelength 260 nm you can calculate the energy and momentum of each photon. You should obtain an energy of about 4.5 eV for this wavelength.
  5. Feb 25, 2014 #4
    you cant visualize frequency in terms of mechanical waves like water waves for instance
    the frequency of an EM wave indicates its strength at some point , and how its strength changes through time in this point
    for instance if you take a point in space in which an EM radiation pass through
    say an EM radiation * for the sake of simplicity* having a frequency of 2 Hz * 2 oscilations / sec *
    that means that the strength of the field is going to go between 1 to -1 * if it's amplitude is 1 * 2 times in one second in this certain point of space
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