From the previous example, we have seen that power in electrical circuits can be found like this:

power = current × voltage or P = I × V

e.g. a 6 V battery provides 2 A to a bright torch.

P = I × V = 2 A × 6 V = 2 C/s × 6 J/C = 12 J/s = 12 W.

Once you're happy with using the formula, we normally write this in its simplest form:

P = I × V = 2 A × 6 V = 12 W

Since we know that current is in A and voltage in V. Power, of course, is always in W!