A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel to the first, the time constant of the new RC circuit will be
A) the same as before.
B) twice as large as before.
C) three times a large as before.
D) one-half as large as before.
E) one-fourth as large as before.

Question

Quizplus · Accepted Answer

The time constant of an RC circuit is given by τ = R*C. When a second capacitor of capacitance 2C is connected in parallel to the first capacitor C, the total capacitance becomes C + 2C = 3C. Therefore, the new time constant is τ = R*(3C), which is three times the original time constant.

A Capacitor C Is Connected in Series with a Resistor