**Current** (denoted as *I*) is a measure of the amount of charge moving through an area at a given time. The SI unit for current is the amp, equal to one coulomb per second. Current is related to resistance (*R*) and voltage (*V*) by the formula

- $ V=IR $

and to power (*P*) by

- $ P=IV $

Current divided by cross-sectional area is called **current density**, and is represented by *J*.