9.1.1—An electric current is a flow of charge carriers

Current is I=∆Q/∆t: the rate at which charge passes a point, measured in amperes, with 1 A=1 C s⁻¹.

Choose a direction convention and distinguish conventional current from the motion direction of negative electrons.

If 12 C passes a wire section in 3.0 s, the current is 4.0 A.

Current is not consumed by a component in a series circuit; charge flow rate is continuous around the circuit.