Capacitors

What They Are

Capacitors store a temporary charge. Which when connected to another component will discharge. It is charged when connected to a cell as electrons move from one plate to the other making a potential difference. It will charge until the p.d is equal to the EMF.

Equations

Initial discharging current:

Time constant:

Also , This is because there is electrostatic repulsion as there are like charges together. But over time there is less charge as the capacitor discharges so the electrostatic repulsion force is reduced so the rate of change of charge decreases.

For charging

is the max charge/total charge of the circuit not in the capacitor at time This is because as it charges the electrostatic repulsion increases making it harder for it to charge.

If you have a capacitor with air in the middle as the insulating material. If you place a flame in the middle, the flame ionises the air and the positive ions will be attracted to the negative plate and will stay there. So the flame stays leaning to one side.