Welcome to You Ask Andy

Jim Johnson, age 12, of Visalia, Calif., for his question:

HOW DOES A NEON LIGHT WORK?  

British chemists Sir William Ramsay and Morris Travers discovered neon in the atmosphere while studying liquid air in 1898. Ramsay had strong feelings about the existence of the gas a year earlier. They found this chemical element makes up almost 18 parts per million of the earth's atmosphere. The name neon means new in Greek.   

Neon is a chemical element that is used primarily for filling tubular lamps and luminous signs. Alone it glows bright red but it will turn bright blue when a few drops of mercury are added. Neon signs are made by first using glass tubes to form letters or patterns. All air is then removed from the tubes  and they are filled with neon gas. Then you add about 15,000 volts of electricity. An electric discharge results and the tube glows.

A neon tube doesn't have a filament such as the one you find in an incandescent bulb. Instead it has two electrodes that are sealed within it. A luminous band between the electrodes is formed by the neon.

Electricity, passing through the neon gas, actually knocks electrons from their orbits. When the electrons fly back into the orbit of its atom, energy in the form of a bright light is released. This light energy is the source of the tube's glow.

Neon is a leftover byproduct of the manufacture of liquid air. It is sold in quart glass containers. Although it is expensive, one quart can be used for 200 to 300 feet of tubular signs.

Neon is odorless and colorless. We call in an inert gas because it doesn't react easily with other substances. Its symbol is Ne.

In the downtown section of Las Vegas there's an area called Glitter Gulch. The neon signs,     extending up several stories, are so thick and bright that on the street at midnight it is as dazzling as it would be under the noontime summer sun. New York's Times Square is another spot where spectacular neon signs cast a magical nighttime spell.    

Neon lights have been used effectively as airplane beacons. The light penetrates fog and pilots can usually see one of the lights more than 20 miles away. Neon light usually shines through when other lights fail.   

 

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