Nullator

In electronics, a nullator is a theoretical linear, time-invariant one-port defined as having zero current and voltage across its terminals.

Nullators are strange in the sense that they simultaneously have properties of both a short (zero voltage) and an open circuit (zero current).

For example, the inputs of an ideal operational amplifier (with negative feedback) behave like a nullator, as they draw no current and have no voltage across them, and these conditions are used to analyze the circuitry surrounding the operational amplifier.

A nullator is normally paired with a norator to form a nullor.

Two trivial cases are worth noting: A nullator in parallel with a norator is equivalent to a short (zero voltage any current) and a nullator in series with a norator is an open circuit (zero current, any voltage).