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B Please help me understand photons

  1. Mar 6, 2016 #1
    I know that photons give off light (in a "stream") but i recently learned that photons can give off all kinds of energy (or waves), like infrared, ultraviolet, gamma rays, and more. My question is: Do photons give off all kinds of radiation or do u have to influence them somehow; How do you make them release certain waves?
  2. jcsd
  3. Mar 6, 2016 #2


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    Staff: Mentor

    Photons don't "give off" or release light in a stream or otherwise. When electromagnetic radiation (infrared, ultraviolet, visible, gamma, X-rays, radio, radar, microwave, whatever) interacts with matter, it always delivers its energy to that matter in discrete amounts; "photon" is the name we use for these discrete amounts of energy.

    If you google for "what is a photon" you'll find some good links.
  4. Mar 6, 2016 #3


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    Hm ... I thought I had already posted this but it was just sitting there. I see Nugatory has already answered so this is pretty much redundant but I'll add it anyway.

    Electromagnetic radiation is a wave and it is an entire spectrum of radiation, the names of some frequency segments of which are "visible light", "ultraviolet", "infrared", and so forth. Photons are an excitation of the wave when it hits an object, so it's not right to say that photons "give off energy"
  5. Mar 6, 2016 #4
    how do people send off all kinds of waves (like the signal for a T.V. or wifi)?
  6. Mar 6, 2016 #5


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    If you're asking how we generate EM waves, the simple answer is that we accelerate charged particles. A radio transmitter accelerates the charges in an antenna back and forth, which ends up creating EM waves at the frequency of oscillation.
  7. Mar 7, 2016 #6
    please be a little more specific: How do they charge particles? How do they accelerate them? what do we use to make this work?
  8. Mar 7, 2016 #7


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    electrons are the charged particles in a conductor that get accelerated

    basically ....
    by supplying an alternating electric field, this accelerates the electrons firstly in one direction and when the polarity of the AC cycle changes,
    the electrons are accelerated in the opposite direction. This creates an electromagnetic field which is radiated away from the conductor

    for further info google subjects like .... electromagnetic field, accelerating electrons, AC current

    Last edited by a moderator: Mar 7, 2016
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