Updated: Nov 18, 2020
Ohm’s principal discovery was that the amount of electric current through a metal conductor in a circuit is directly proportional to the voltage impressed across it, for any given temperature. Ohm expressed his discovery in the form of a simple equation, describing how voltage, current, and resistance interrelate:
In this algebraic expression, voltage (E) is equal to current (I) multiplied by resistance (R). Using algebra techniques, we can manipulate this equation into two variations, solving for I and for R, respectively:
I=E/R ; R=E/I
Analyzing Simple Circuits with Ohm’s Law
Let’s see how these equations might work to help us analyze simple circuits:
In the above circuit, there is only one source of voltage and only one source of resistance to current. This makes it very easy to apply Ohm’s Law. If we know the values of any two of the three quantities (voltage, current, and resistance) in this circuit, we can use Ohm’s Law to determine the third.