A 4.0 μF capacitor is connected in series to a resistor.If an emf source is connected in series to this arrangement,and if the voltage drop across the capacitor is one-half the applied emf .0 ms after the emf source has been connected,what is the resistance of the circuit?
A)2.9 kΩ
B)1.4 kΩ
C)0.35 kΩ
D)0.72 kΩ

Question

Quizplus · Accepted Answer

The voltage across the capacitor in an RC circuit is given by Vc = V(1 - e^(-t/RC)). At t = 0 ms, Vc = 0.5V, so 0.5 = 1 - e^(-0/RC). Solving for R gives R = -t/(C * ln(0.5)) = 2.9 kΩ.

A 40 μF Capacitor Is Connected in Series to a Resistor