Neon Light

A big city at night is likely aglow in neon lights. Neon lights emit light when electrons move through a gas or a mixture of gases inside glass tubing. Many lights called neon lights contain gases other than neon. Often, other gases including helium, argon, and krypton are used in neon lights. Helium gas gives off a pink light. A mixture of argon gas and mercury vapor produces greenish-blue light. Krypton gas produces a pale violet light. Pure neon emits red light when electrons flow through the gas. Each kind of gas emits photons of different energies, and therefore different colors. The different photons emitted combine to give each glowing gas a distinctive color. The color of glass used to make the tube can also affect the color of the light.

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