Chapter 21 Current, voltage and resistance

21.1 The nature of electric current

Current is simply the rate of flow of electric charge. Thus, if more charge moves in a given time, more current will be flowing. If no charge moves then no current is flowing. The unit of electric current (defined in the previous chapter) is the ampere, A, and one ampere is equal to one coulomb of charge flowing past a point in one second.


where t = time in seconds and Q = charge in coulombs.

So, for example, if a steady current of 5A flows for two minutes, ...

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