Visible Light and Antennae
Date: Fall 2013
I have been studying electromagnetic radiation lately and I was wandering why visible light cannot be emitted from an antenna. We emit lower electromagnetic wavelengths with antennas so why not visible light? Does the antenna have to be a certain size for that to be possible? If it is not possible to use an antenna, what do they use to emit UV, X-ray, and Gamma radiation? Could those methods be used to emit light?
Thanks for the questions. Actually, visible light can be emitted from an antenna--it is called a spark. Do not do this at home...but you can get sparking from metal when you place it in a microwave oven. This is visible light being emitted from an antenna. UV, X-rays, and gamma radiation occur because charges oscillate really fast. These charges do not exists in a metal antenna, but exist in free space. The situation is a bit more complicated for gamma rays since there are electric and magnetic oscillations in the nucleus. But the same principle applies.
I hope this helps.
Most antennae do not emit visible light because they are not designed to. Light bulbs are.
The wavelengths and modalities are different.
Antennae will emit electromagnetic radiation in the X-ray, UV range; but they are designed to do so.
Peter E. Hughes, Ph.D. Milford, NH
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