I–V characteristic

An I–V characteristic normally places potential difference on the horizontal axis and current on the vertical axis. An ohmic conductor at constant temperature produces a straight line through the origin. It is therefore a linear circuit element.

Measuring current and potential difference together lets you explore a component’s I–V characteristic: how much current flows at each potential difference.

A fixed resistor at constant temperature is an ohmic conductor. Its I–V characteristic is a straight line through the origin: doubling the potential difference doubles the current.