Ohm's Law

Example

Ohm’s Law is a relationship between the voltage, current and resistance of a resistor:

V = I R

where:

V = voltage across the resistor (in volts or V)
I = the current through the resistor (in amps or A)
R = the resistance of the resistor (in ohms or Ω).

The voltage across the resistor in the diagram at right is 12V. The resistance of the resistor is 3Ω. Solving Ohm’s Law for the current gives:

I = V/R

Substituting gives:

I = (12V)/(3Ω) = 4A.