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

${\displaystyle V = IR}$

and to power (P) by

${\displaystyle P=IV}$

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