How Everything Works
How Everything Works How Everything Works

Question 231

How do collisions with tungsten atoms in the filament of a flashlight convert the current's electrostatic and kinetic energies into thermal energy?
When the electrons moving through the tungsten filament collide with the tungsten atoms, they do work on those tungsten atoms. Although the atoms are very massive and the electrons bounce off of them like Ping-Pong balls from bowling balls, the atoms do jiggle about after being struck. Bombarded by a steady stream of electrons, the atoms in the tungsten begin to vibrate harder and harder and soon become white hot. The electrons leave the tungsten filament with relatively little energy left-they use almost all of their kinetic and electrostatic potential energies to get through this gauntlet of tungsten atoms.

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