Topic 16. Capacitors
A simple capacitor consists of two metal plates with a layer of insulator between them.
The insulating layer may be a thin sheet of plastic, but some types of capacitor have a layer of air instead.
If a capacitor is connected to a source of DC electric power, electrons accumulate on the plate that is connected to the negative supply terminal. These repel electrons from the opposite plate. The repelled electrons flow toward the positive terminal.