How an AC capacitor differs from a DC capacitor
Before you can understand what the difference is between an AC capacitor and a DC capacitor, you first need to know what a capacitor actually is. It is the name given to a device that generates electricity. It consists of an insulating medium that separates a pair of conducting plates. How much value a capacitor has depends on several factors:
- The surface area of the plates
- The distance between the plates
- The thickness of the insulating medium
The first capacitor was invented in 1745 by a German scientist named Ewald Georg. In his experiments he half-filled a glass jar with water and then sent an electrical charge through the water by sealing the jar with a cork that contained a wire. He then charged the wire with a source of static electricity and since the wire was in the water, it became charged with electricity.
The electrical charge in a capacitor is called capacitance. Each capacitance has a value that is equal to a microfarad, which is one-millionth of a farad.
Based on this explanation, you can see that a capacitor is a type of battery. The difference is that a battery has two terminals – one which produces electrons and one which absorbs electrons. A capacitor on the other hand only stores electrons. They are widely used in every day appliances that you use every day – computers, televisions, remote controls, alarms and many others.
The difference between AC and DC capacitors
When you connect a capacitor to a battery, the battery will charge it and when it is fully charged that will be the end of the flow of current. Therefore the DC current will be blocked from the battery. The electrical charge that is in the capacitor is the AC current and it will continue to flow without interruption.
The connection from the battery to the capacitor allows the DC current to flow into the device. However as soon as the terminals on the capacitor have the right amount of current, they will shut off. If you disconnect the battery at this point, the capacitor will still retain its charge and the AC current will continue to exist. However, if you connect an AC source to the capacitor the current will only continue to flow to the device as long as there is a source of power.