Discharging a capacitor

Need to know

What you need to know

• 19.3 Discharging a capacitor.
• When a capacitor is being charged, the electrons flow from the positive to negative plate.
• When the capacitor is being discharged through a resistor, the electrons flow back from negative plate to the positive plate until there are equal number of electrons on each plate.
• At the start of the discharge, the current is large and gradually falls to zero.
• As a capacitor discharges, the I, V and Q all decrease exponentially.
• This is represented by an exponential decay in the graph above.

Explanation

Discharging a capacitor

1. 19.3 Discharging a capacitor.
2. When a capacitor is being charged, the electrons flow from the positive to negative plate.
3. When the capacitor is being discharged through a resistor, the electrons flow back from negative plate to the positive plate until there are equal number of electrons on each plate.
4. At the start of the discharge, the current is large and gradually falls to zero.