Sep 082014

# Ohm’s Law and the Electric Power

**Ohm’s Law** relates in one equation the voltage, the current and resistance. Resistance = Resistor’s value.

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 = V
^{2}/R, P = I^{2}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 = V
^{2}/P, R = P/I^{2}. (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}.