Question

1) What is the current through and voltage across a capacitor after it is fully charged in a DC circuit?

a) I=0, V=0

b) I=0, V=max

c) I=max, V=0

d) I=max, V=max

2) What is the current through and voltage across a capacitor after it is fully discharged?

a) I=0, V=0

b) I=0, V=max

c) I=max, V=0

d) I=max, V=max

Answer 1

(1) What is the current through and voltage across a capacitor after it is fully charged in a DC circuit?

I = 0, V = max

Option (b) : it will be correct.

Explanation : Once the voltage at the terminals of a capacitor, V_C is equal to the power supply voltage, V_C = V.

Then, the capacitor is fully charged and the current stops flowing through a circuit.

Therefore, the charging phase is over.

A capacitor is equivalent to an open-circuit to direct current, R = because once the charging phase has finished, no more current flows through it. The Voltage (V_C) on a capacitor cannot change abruptly.

(2) What is the current through and voltage across a capacitor after it is fully discharged?

I = max, V = 0

Option (c) : it will be correct.

Explanation : The discharging current is maximum at the starting of a process of discharge but the discharging current slowly decreases until it becomes zero and the capacitor becomes fully discharged.

We know that, V = I_C R + V_C

Where, V_C = voltage supplied to the capacitor which is zero in the case of discharging

I_C = positive (charging current or negative of discharging current) current through capacitor

V = voltage between terminals of the capacitor