The Ohm's law power triangle

An easy way of remembering the formula is to use the Ohm's law power triangle.

Ohm's law triangle

To help you remember the formula, draw an Ohm's law power triangle. Then, place your thumb over the unit you wish to determine. The appropriate formula is shown, as explained below.

If you cover P for power then the the formula is IV (P = I x V).

If you cover I for current then the the formula is P over V (I = P / V).

If you cover V for voltage then the the formula is P over I (V = W / I).

If any two values in a circuit are known, the third value can be calculated.