Question

The switch has been in position 'A' for a long time. If the switch is quickly moved to position 'B', what is the time required to fully charge the capacitor?

a) Instantaneous
b) Depends on the capacitor's size
c) Long duration
d) Can't be determined

Answer 1

The time to fully charge a capacitor when switching from 'A' to 'B' is dependent on the RC time constant, which is a product of the circuit's resistance and the capacitor's capacitance, taking about 5 time constants to reach nearly 100% charge.

Step-by-step explanation:

The time required to fully charge a capacitor when the switch is moved from position 'A' to 'B' depends on the capacitor's size and the resistance in the circuit. The key concept to understand here is the RC time constant, which is the product of the resistance (R) and the capacitance (C) of the circuit. The time constant (T) is the time required for the capacitor to charge to about 63.2% of its maximum charge, or for the voltage across the capacitor to reach about 63.2% of its maximum value. To completely charge the capacitor, or reach nearly 100%, takes approximately 5 time constants. Thus, the correct answer to the given question is that the time required to fully charge the capacitor is dependent on the capacitor's size and circuit resistance.