Electrical Engineering ⇒ Topic : Bilateral and Unilateral circuit

In the nineteenth century, a German philosopher, George Simon Ohm discovered that the current through a conductor, under constant temperature conditions, was  proportional to the potential difference across the conductor.

Expressed as an equation, Ohm's law become

               / = V
                    R

where, / is the current in amperes, Vis the potential difference in volts and R is the resistance in ohms.

This fact can be demonstrated by connecting a voltage source (V), an ammeter (A) and a load. Different currents can be obtained by varying  the load resistance. For example, if the voltage across the load is 12 V and the load resistance is 3 S2, the current through the circuit is 12/3 = 4 A. If the load resistance remains constant at 3 S2, in accordance with Ohm's law, the current will double if the voltage doubles or will reduce to half if the voltage is reduced  by half. Thus, if the voltage across the load reduces to zero, the current also  becomes zero.