| 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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