Electrical power: P = VI

Set the voltage and current to get the power, and see how the three power formulas link together.

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Questions students ask

How do you choose a fuse?

Work out the normal current, I = P ÷ V, and pick the next fuse rating above it, for example a 13 A fuse for a 2.5 kW kettle on 230 V (about 10.9 A).

What formula does it use?

P = VI = I²R = V²/R, in watts.

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