Electrical Current

Upon turning on a lamp, Raymond wonders, “About how fast do the electrons in house wiring move as they provide electrical energy to the lamps and other

Answer

The electrons in house wiring move at a snail’s pace, with an average drift velocity of about a millimeter per second. These electrons, which are free to move in the metal wires, are distributed throughout, so when the switch is closed to make a complete circuit, they move en masse, sort of like water passing through a continuous hose that closes on itself. The electron velocity is limited because its negative electric charge interacts with the lattice of positive ions during the movement.

In addition to having a drift velocity, the electrons experience a random sequence of pinball-like collisions to change their speeds and directions, essentially behaving as a free electron gas. Consequently, the host metal gains some thermal energy, and its temperature rises. If a lamp is the incandescent type, the tungsten alloy filament will gain enough energy by this process to dramatically increase its temperature to a new equilibrium temperature of about 2000 K to glow in the visible and the infrared.