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Homework Help: A Lenz Law Question

  1. Jan 11, 2009 #1
    A circuit contains a resistor and an uncharged capacitor. Pointing into the plane of the circuit is a uniform magnetic field (B). If the magnetic field increases in magnitude with time, which plate of the capacitor (top or bottom) becomes positively charged?

    I don't understand how the hand rules play into this question, because of the capacitor. And I don't understand how I'm supposed to figure out which plate is positive and which is negative. Please help me out?

    Thanks in advance, guys. :shy:
  2. jcsd
  3. Jan 11, 2009 #2


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    Homework Helper

    A capacitor acts like a direct connection when it is uncharged, so ignore it while you use the hand rule to determine the direction of the current. Charge doesn't actually pass through a capacitor, so if positive current flows into a capacitor, it will charge that side of the capacitor positively.
  4. Jan 11, 2009 #3
    OH. It makes this question so much easier now, thanks. bundles.

    I've come to determine my upper plate is negative cause the electrons flow into it.

    again, thanks so much.
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