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Name: Erik
Status: student
Grade: 6-8
Location: Outside U.S.
Country: USA
Date: Spring 2013

We hear about things that are red hot, and white hot. My stove has blue hot flames. Can things be green hot too? Like there is a red dwarf and a white dwarf star, but no green dwarf stars. How come?

Erik, In most cases where a heated material emits light, it emits a range of colors. ?Red hot? is a range from infrared to red. It looks red because we cannot see the great amount of infrared light that goes with it. ?Blue hot? has blue as the low end. Ultraviolet light is also emitted, but we cannot see that either. When centered in the range of visible light, all colors might be emitted. When all colors are combined, the light looks white.

Some materials emit only a narrow range of color. This is why different materials burn at different colors. I believe that burning copper emits green light. Still, many common materials emit a range of colors when heated.

Dr. Ken Mellendorf Physics Instructor Illinois Central College

The colors your are seeing are due to two different phenomena. The 'red-hot' or 'white-hot' designations are due to black body radiation, which you can read about on-line. The colors of flames are due to ionization of components of the fuels or the air around the flame. Different chemicals can cause different colors of flame. For more information, read more about "flame color" and "chemical (inorganic) qualitative analysis".

Hope this helps, Burr Zimmerman

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