A portion of the current-voltage characteristic of certain devices, such as
the thyristor, the tunnel diode and the magnetron, has a negative slope, that
ls, the current decreases with increasing applied voltage or the voltage
drops when the current increases. This behaviour is, of course, opposite to
that of an ohmic resistance. Whereas an ohmic (positive) resistance
consumes power, a negative resistance appears to supply power. Negative
resistance may be simulated electronically as described in this article.