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Eddy current braking

  1. Mar 19, 2008 #1
    Hello all :)
    I'm doing some coursework on eddy current braking atm and I just need to clarify that I have the right idea about how the concept works.

    Right, I know that when a conductive plate passes through the poles of a magnet, the change in magnetic flux induces eddy currents in the conductor. And that these travel in loops defined by Lenz's law so that the eddies will swirl in a way so that their own magnetic field is opposed to the change in flux that caused them.
    But what exactly causes the loss of speed of the plate?

    I understand that the eddy currents will come across some resistance and so some energy will be dissipated as heat. But is that it? What's the deal with the Lenz's law thing then... I mean, why is that important that we know which way the electrons loop, if all that matters is that the currents dissipate energy through resistive losses and this is equal to the kinetic energy lost?

    Am I at all right in thinking that because the eddy currents loop in a way to oppose the change in flux, that there is some sort of magnetic repulsion/attraction thing going on? Such as,the front is attracted back to the magnet and at the back it is repelled by the magnet? And these combined cause it to slow aswell?

    That was my initial thought but all I've ever found about it is talk of lenz's law and then resistive losses and I can't find any places to confirm or reject my confusion. Any help would be very gratefully received.
    thank you
  2. jcsd
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