- #1
QuarkCharmer
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Homework Statement
A 5 micro farad capacitor is in series with a resistor, a switch, and a 12VDC ideal battery. The switch is closed at t=0s. The time constant of the circuit is 4.0s.
Determine the value of the resistance R?
Homework Equations
The Attempt at a Solution
From another example of a series circuit with a resistor and cap and switch, we found the equation:
[tex]q(t) = CE(1-e^{\frac{-t}{\tau}})[/tex]
where tau is the time constant, and is substituted for RC in the equation. Now to me, this seems simple, tau = RC...
so [tex]R = \frac{\tau}{5.0*10^{-6}}[/tex]
where tau = 4.0 seconds
which is like 800,000 [itex]\Omega[/itex], which cannot be right! How do I tackle this problem?