|MadSci Network: Engineering|
I also tried searching for +radio_waves on the internet and the MadSci Archives and had trouble finding anything until I broadened my search to +electromagnetic_spectrum Radio waves are just one example of electromagnetic radiation. The electromagnetic spectrum represents all forms of electromagnetic radiation from shortest to longest wavelength. The particular reference text I used, Eisberg and Resnick's Quantum Physics, shows cosmic rays at the short end and something referred to simply as power waves (longer wavelengths than radio waves) at the other end. A related website with a picture representation of an electromagnetic wave is at http://www.geo.mtu.edu/rs/back/spectrum/ Another interesting website, also announcing a related television show on 12 December 2000, is http://www.altair.org/index.html But, back to your basic question - how are radio waves produced. Your best bet is to find a high school physics textbook and look up electromagnetism, electromagnetic radiation, or other related terms. In general, changing an electric field gives rise to a magnetic field and changing a magnetic field gives rise to an electric field. If you alternate the direction of current flow in an appropriately designed radio transmitter, the result is a continuously varying electric field AND a continuously varying magnetic field. The resulting 'wave' is often illustrated by showing a sinusoidal electric field along one axis, and a sinusoidal magnetic field traveling in the same direction but oriented normal to the electric field (see the illustration in the first web reference provided above). If you are not familiar with electromagnetism - and most of us aren't - the above will not make a lot of sense, but try the web references above and find yourself a copy of the textbook being used for physics in your school. There is a lot of conceptual framework to be established on the way to understanding electromagnetic radiation. Thanks for your question. sid
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