What is the Difference Between an Ohmic and Non-Ohmic Conductor?

Ohmic conductors are characterized by the fact that the set voltage \(U\) on the ohmic conductor is proportional to the electric current \(I\), where the proportionality constant is the electric resistance \(R\):

If the voltage \(U\) is doubled, then the current \(I\) through the conductor is also doubled.

The resistance \(R\) of an ohmic conductor is constant and the U-I graph is a straight line.

Non-Ohmic conductors, on the other hand, are all conductors that do not satisfy Ohm's law 1. This means that the doubling of the voltage \(U\) does not have to result in the doubling of the current \(I\). In illustration 2, the U-I graphs of non-ohmic conductors are sketched as examples: Transistor graph (1), gas discharge graph (2) and diode graph (3).

For non-ohmic conductors, the resistance depends on the voltage and the U-I graph is not a straight line.