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Capacitors Explained for Engineers

Introduction to the Capacitor in Electrical Engineering

​We can think of capacitors are short term ‘charge-stores’. In other words, capacitors just store charge inside them. A capacitor consists of two metal plates separated by a layer of insulating material called a dielectric.

There are 2 types of capacitor:

  1. Electrolytic capacitors. These hold much more charge and must be connected with the correct polarity, otherwise they can explode.

  2. Non-electrolytic. These hold less charge and can be connected either way round in a circuit.

How Does a Capacitor Work?

When two conducting plates are connected to a battery, electrons move towards one plate. The positive plate loses electrons , eventually leaving both plates with equal and opposite charge, +Q and -Q. When a capacitor is charged, we say that the capacitor has charge Q.