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Electromagnetic induction

  1. May 30, 2010 #1
    I understand what electromagnetic induction is and its applications. However, I don't understand why this occurs- is there an explanation for why a changing magnetic flux induces an electric current?

  2. jcsd
  3. May 30, 2010 #2


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    Welcome to PF!

    Hi bgorm! Welcome to PF! :smile:

    A changing magnetic field will make any charge move … conducting wires are full of electrons, which have charge, so they move, which is current. :wink:
  4. May 31, 2010 #3

    Thanks for your reply. I understand what you are saying. My question is more do physicists know why this occurs. For example, physicists know about the effects of gravity but don't understand what causes it. I was curious if this is also true for electromagnetic induction.

  5. Jun 1, 2010 #4
    bgorm, the faraday's law u stated was first experimentally observed & was theoretically explained more than a century later by quantum electrodynamics. (a graduate level course). there's no simpler explanation.
    similar to that of a moving charge producing a magnetic field.

    u were right about knowing the effects of gravity but not knowing their cause. there is no quantum theory of gravity yet & this is a topic many researchers are pondering over.
    fortunately we have a quantum thory for EM - quantum electrodynamics.
  6. Jun 3, 2010 #5
    EMI is described by 2 laws, Ampere & Faraday. AL relates the flux with the currents, & FL relates the flux with the voltages. In addition, the law of Lenz plays an important role, as well as conservation of energy & Ohm's law, which are universal.

    These laws are axioms, meaning that they are not derived from anything more fundamental. Lorentz later published his force equations which describe the force acting on an individual charge in the presence of E & B fields.

    We know that e/m induction takes place, & we can predict its behavior mathematically, but I don't think anyone can say WHY. It's like asking why gravity exists, or why electrons & protons have charge while neutrons don't. It just happens to be that way. Sorry if that is not the answer you are looking for, but that is quite a tough question.

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