The power formula expresses fundamental relationships among power, current, and voltage. On occasion, you may be asked to calculate any one of the three variables in this equation, given the other two. As a result, good mnemonics to remember is the PIV triangle.
PIV triangle for the Electrical Power formula (Diagram)
How to use the PIV Triangle for the Electrical Power formula?
If the two variables you know are across from one another, then multiplying them will get you the third. If you know the current (I) and the voltage (V) in a given circuit, you can calculate the electrical power (P) by multiplying the current and the voltage.
If the two variables you know are above and below one another, then you can get the third variable by dividing the one above by the one below. For instance, if you know the power and the current in a given circuit, you can calculate the voltage by dividing the power by the current.