Ohm’s Law and the Electric Power
A more complete expression of Ohm’s Law is achieved using the electric power formula. Using the known formula of power: P = VxI, (Power = voltage x current), and its variants: V = P/I and I = P/V, additional equations are obtained.
These new equations allow us to obtain the values of power, voltage, current and resistance, with only two of the four variables.
- Solving for P, we get: P = V2/R, P = I2 x R, P = V x I. (watts)
- Solving for I, we get: I = V/R, I = P/V, I = (P/R)1/2. (amps)
- Solving for R, we get: R = V/I, R = V2/P, R = P/I2. (ohms)
- Solving for V, we get: V = (PxR)1/2, V = P/I, V = IxR. (Volts)
The diagram shows a complete summary of the formulas, arranged so that it is easier to memorize.
Note: The square root = ( )1/2.