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Skin effect and polarisers

  1. Jul 22, 2014 #1
    Hello forum,
    I have a few doubts on EM.
    1. The skin depth formula for constant current(DC) shows that there can be current uniformly distributed through the cross-section of a conductor.However as there can be no electric field within a conductor(as per Maxwell's equations) there can be no force on the electrons within a conductor and the electrons do not move inside the conductor and so there is no current inside a conductor.These two facts seem contradictory.
    2. Also,if it is so that current flows inside a conductor,the drift velocity of electrons is too slow.Is it the EM wave on the periphery of the conductor that causes a bulb to light as soon as it is switched on?
    3. I am a bit confused about the working principle of wire grid polarizers. Maxwell's equations says that there shall be a non zero magnetic field on the surface of a conductor as an EM wave is incident on it.That means there shall be a varying surface current density(i.e. motion of electrons).As those grids which have their grids parallel to the E vector allow that and thus satisfy Maxwell can reflect EM waves.Please correct me if I am wrong.

  2. jcsd
  3. Jul 22, 2014 #2


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    I don't think this applies to an electronic circuit, as it isn't a static situation.

    The drift velocity of the electrons may be slow, but current flows throughout the circuit all at once. Consider turning on the hot water faucet in your kitchen sink. Water starts to flow out of the faucet immediately, but it takes a while for the water from the hot water heater to get through the pipes to the faucet, so you have to wait a bit to get hot water. Current is similar. The drift velocity is slow, but when you initially flip the switch you have current flowing everywhere, including through the bulb.

    I can't answer number three, sorry.
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