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Capacitor and displacement current.

  1. Feb 21, 2013 #1
    1. The problem statement, all variables and given/known data

    a capacitor of capacitance 'C' is being charged across a dc source with an ammeter . will the ammeter show a momentary deflection during the process of charging? if so, how would it and the resulting continuity of current in the circuit be explained ?

    2. Relevant equations

    maxwell's displacement current equation

    3. The attempt at a solution

    continuity is bcoz conduction +displacement current is same everywhere in circuit but what about momentary deflection ?
     
  2. jcsd
  3. Feb 22, 2013 #2
    You basically have a RC circuit with very little resistance so that the voltage over the capacitor , VC,will build up very fast during the charging process according to

    VC = E(1 - e-t/RC)

    where E is the emf of the dc source. The voltage of the capacitor opposes that of the dc source and the current will stop when the two voltages are the same - that is the charging process stops. The charge build up on the capacitor will be

    q = CVC

    so that the current will be decaying exponentially with time

    i = dq/dt = E/R e-t/RC
     
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