Current, up close

Current is the rate at which charge flows, measured in amperes (amps, A). It tells you how much charge passes a point each second. Scale matters here: a kettle pulls several amps, a phone charger around 1–2 A, and a single LED just sips around 0.02 A — that is 20 milliamps (mA). Remember 1 A = 1000 mA.

Current is a flow rate, like litres per second, not the speed of an individual charge carrier. In a wire, the amount of mobile charge per volume, the cross-sectional area and the drift speed together determine current.

Now a famous head-scratcher: conventional current is drawn as flowing from + to –, even though the electrons physically move the other way. The convention was set before anyone knew electrons existed. We keep it because all the math still works out — just treat the arrow as the direction positive charge would go.