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Confusion with Resistance and Current 
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#1
Nov1710, 09:42 AM

P: 2

1. The problem statement, all variables and given/known data
This is my question not from homework or anything. If a capacitor has stored a charge in a circuit and is discharging, and a resistor is attached to this circuit, what affect does this have on the discharge time? If the resistor makes it harder for a current to flow, does this mean the current takes longer to be used up? Also I can't differentiate between charge and voltage in a capacitor. 2. Relevant equations V=IR C= Q/V Q=It Any help please and thanks, detailed as. 


#2
Nov1710, 10:21 AM

HW Helper
P: 3,394

You are completely correct about the capacitor current. For a resistor connected across a charged capacitor, the current as a function of time is an exponential decay: I = V/R*e^(t/(RC)). The product RC is the time to fall to 63% of the initial value. RC is called the "time constant"
http://en.wikipedia.org/wiki/Time_constant The charge and potential on the capacitor are directly related by one of your formulas, Q = C*V. As the charge increases, so does the voltage. 


#3
Nov1710, 10:28 AM

Sci Advisor
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P: 6,653

AM 


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