Chapter 17 science

Neon Light

A sealed glass tube that contains neon gas. When an electric current passes through the neon, particles of the gas absorb energy. However, the gas particles cannot hold the energy for very long. The energy is releases in the form of light.

Fluorescent Light

A bulb that contains a gas and is coated on the inside with a powder. When an electric current passes through the bulb, it causes the gas inside to give off ultraviolet rays. When the ultraviolet rays hit the powder in the tube the powder gives off visible light. They give off the most of their energy as visible light and only use a little energy as infrared rays. Do not get as hot and usually last longer, use less electrical energy, and are very efficient.

Vapor Light

A bulb that contains neon or argon gas and a small amount of solid sodium or mercury. When an electric current passes through the gas the gas heats up. The hot gas then heats the sodium or mercury. The heating causes the sodium or mercury to change from a solid into a gas. They require little electrical energy to give off a great deal of light so are quite efficient.

Tungsten-Halogen Bulb

A bulb that has a tungsten filament and contains a halogen gas such as iodine or bromine. The filament of this bulb gets much hotter than in an ordinary bulb, so the bulb looks whiter. More efficient than ordinary bulbs because they give off more light and less heat but get so hot they must be kept away from materials that might catch fire.

Ordinary Light Bulb

Light bulb that contains thin wire called filament made of tungsten. When an electric current passes through the filament it quickly heats up and becomes hot giving off white light. Not efficient. Less than 10% of their energy is given off as light instead most is given off as infrared rays which is why it gets so hot.

Incandescent Light

a light bulb that glows when a filament inside gets white hot.