How about an example of a non-ohmic element? The filament in an incandescent bulb does not have a constant resistance. If you take a bulb and increase the voltage across it, the current increases too.

Linear resistance may have either an ohmic positive I-V slope or a negative slope. A typical, lossy resistor is by definition the ratio of voltage over current (R = E/I, according to Ohm’s Law).

A group of researchers in England and Spain has discovered that certain barium titanate ceramics do not follow Ohm's Law. Applying a voltage to them gradually changes their electrical resistance.

The SBS-6500 Internal Resistance tester is designed to incorporate the entire history of multiple battery strings’ internal resistance, voltage and temperature readings. This includes a complete ...

The time to stabilize and the final, steady-state resistance were, however, both temperature-dependent. "I was not immediately convinced myself about the non-Ohm's Law behavior," said West, Professor ...