Glowing, Glowing, Glowing, . . . . Gone?


One type of glow occurs when something gets hot, like the top of an electric range or an incandescent light bulb. The heat energy shows up in the random motion of all particles (molecules, atoms, and electrons) that make up the material and can come in all kinds of sizes - making the light that results from this come in all kinds of wavelengths! This light forms a continuous spectrum of colors, like a rainbow. The brightness of the light changes with color as well, with the brightest color depending on the temperature.

Incandescent Light Bulb - Hot Glow
Light from a Hot, Glowing Object

As the temperature gets hotter, the color shifts from red toward blue through the rainbow of colors. The overall brigthness increases quickly with temperature as well. When the temperature doubles, the total light power radiated increases up to a factor of 16 times! (At lower temperatures, when we don't see a glow, the object may be glowing in infrared wavelengths that we usually call radiant heat.)


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