A capacitor of capacitance is charged to a potential and then discharged through a resistor . At time (one time constant), what fraction of the initial charge remains on the capacitor?
Answer and explanation
Correct answer: D.
- Step 1: In an discharging circuit, the charge decays exponentially according to .
- Step 2: At time , the exponent is .
- Step 3: Compute the remaining fraction: .
Answer
().
Why not the others: corresponds to the half-life ; is the charge accumulated during charging after one time constant; corresponds to two time constants ().
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