Flip the switch. The light comes on at once.

Inside, the wire is already full of electrons.

Each one drifts along at a crawl: 0.04 mm a second.

Leave the light on for an hour: it moves 13 cm.

So how does the light come on at once?

The push runs round the loop at nearly light speed.

Every electron in the loop starts moving at once.

Double the push, the voltage: twice the current.

Add resistance, and the current falls.

In the thin filament, they squeeze through faster.

They hit its atoms. That becomes heat and light.

Break the loop, and everything stops at once.

Electricity is not electrons racing. It is a push round a loop.