Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How Do Photons Carry Electromagnetic Force?

  1. Mar 1, 2010 #1
    I've heard that accelerating charge generates photons. How do the photons create electromagnetic force, how do they differentiate between positive and negative charges, and how would electromagnetic force work in the case of stationary particles?

    Are electrons so much more densely charged because they move faster?
  2. jcsd
  3. Mar 2, 2010 #2
    No, the accelerating of a charged particle such as an electron does not increase the charge of the electron, it merely increases the energy carried by the electron, as a result it releases this excess energy as photons.

    Photons do not create EM force, they are the EM force as it were, when negative charged particles approach each other they exchange photons, therefore giving each accelerating each other away from one another.

    And finally Yes charged particles can emit photons when stationary.
  4. Mar 2, 2010 #3
    I am surprised about how one resting charged particle emit photons.

    Could you give some tips to understand this state?
  5. Mar 3, 2010 #4
    if you are meaning a particle on its own, no other particle anywhere in the universe, then it would not according to the transactional interpretation of quantum theory, and Richard Feynman be able to emit any photons.

    If however you are looking at a stationary charge and a charge (both of the same, positive say) that is moving towards the stationary object, it was easier for me to think about it in terms of fields(force fields as it were).
    When the moving charge enters the field of the stationary charge, it causes a disturbance in this field, propagating as a photon which passes energy to the stationary charge.
    And vice versa between the particles until both charges are out of range of the others field, the stationary charge is no longer stationary but has taken energy from the moving charge which is now moving at a slower rate on a different course.

    http://en.wikipedia.org/wiki/Electromagnetic_field - the introduction here says a bit more

    Hope this helps :D
  6. Mar 3, 2010 #5
    I see. The fact that the resting charged particle can emit photon depend on the existence of the other moving particle. Could I understand your statement like this?
  7. Mar 4, 2010 #6
    in a system of just those two particles, that is a way of understanding it yeah
  8. Mar 8, 2010 #7
    A photon on its own do not deliver any photons. All photons are defined, and only defined, in their interactions. there is no way I know of to define a photon without that interaction. If there was all discussions about their possible paths etc would be moot. As for how two 'photons' create a new photon?


    It's one of those facts of nature :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook