A capacitor C = 100 µF is connected to three resistors, each 1 kΩ, and a 9 V battery as shown. After the switch has been closed for a long time, it is opened. Find the discharge time constant.

Question

G1 Physics · Accepted Answer

After opening the switch, replace the resistor network seen by the capacitor by its equivalent discharge resistance. The shown network gives R(th)=0.5 kΩ, so τ=R(th)C=(0.5 kΩ)(100 µF)=50 ms. Hence D.