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Homework Help: Current versus voltage, Very Easy (but stuck)

  1. Nov 16, 2009 #1
    1. The problem statement, all variables and given/known data
    The problem gives a graph of Emf versus time, in a circuit consisting of capacitor C and voltage source e. It asks to draw the time dependence of the current I in the circuit.

    2. Relevant equations
    The graph looks like a trapezoid, positive slope starting at Emf=0 t=0, getting to t1 where the slope becomes 0, until t2, where it becomes a negative slope, and travels to t4 where it reaches Emf = 0

    3. The attempt at a solution
    I know for Ohms law it states V = I/R, but there isnt a Resistor in the circuit given. Would this just show that the current graph should look exactly the same as voltage graph?

    Please help, thank you.
  2. jcsd
  3. Nov 16, 2009 #2


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    Science Advisor
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    Gold Member

    You can put a resistor in (after all the leads always have some resistance), but this will not change what the drawing of the time dependence of the current looks like.

    How about some equations to begin with? How are emf, capacitance and current related? You need two equations for starters.
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