Question

Why do we need capacitors?

Answer 1

A capacitor is a bit like a battery, but it has a different job to do. A battery uses chemicals to store electrical energy and releases it very slowly through a circuit. A capacitor generally releases its energy much more rapidly. If you're taking a flash photograph, for example, you need your camera to produce a huge burst of light in a fraction of a second. A capacitor attached to the flashgun charges up for a few seconds using energy from your camera's batteries. Once the capacitor is fully charged, it can release all that energy in an instant through the xenon flash bulb.

Although capacitors effectively are used to store charge, they can be put to all sorts of different uses in electrical circuits. They can be used as timing devices (because it takes a certain, predictable amount of time to charge them), as filters (circuits that allow only certain signals to flow), for smoothing the voltage in circuits, for tuning (in radios and TVs), and for a variety of other purposes.