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B Electric field and conductors

  1. Oct 31, 2016 #1
    hi, i want to ask explanation that if in front of electric fields lines comes a metal plate, than as far i know electric field does not pass through it, but how would i expalin as electric field can exert force on free electrons.
  2. jcsd
  3. Oct 31, 2016 #2


    Staff: Mentor

    Your question does not make sense to me. It sounds like asking why you stop seeing things when you put on a blindfold.
  4. Oct 31, 2016 #3
    There is no electric field inside a conductor in static equilibrium but once you allow the charges to move in a certain direction like creating a circuit, electric fields can exist inside conductors.

    That is what I understood from your question.
  5. Oct 31, 2016 #4


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    Staff Emeritus
    Science Advisor

    The external electric field attracts the electrons, but they are not able to leave the metal as the positively charged ions of the metal also attract them. Upon application of the external electric field the electrons will move until the two forces are balanced out. Since this charge separation creates an electric field pointed in the opposite direction of the first and of the same magnitude, the two fields cancel each other out inside the conductor. This wouldn't necessarily mean that the field on the other side of the plate is cancelled, however. In general I don't think that's true.
  6. Nov 1, 2016 #5
    thanks that helps , actually i am figuring out why EM waves cannot pass through metal interface.
  7. Nov 1, 2016 #6


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    Staff Emeritus
    Science Advisor

    The electrons in the metal are easily accelerated under the influence of the EM wave. This makes it very easy for the metal to absorb the the wave or for the electrons to undergo a collective oscillation that tends to reflect the wave.
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