MadSci Network: Engineering
Query:

Re: How does radio waves works, Including picture of radio Waves .

Date: Tue Dec 5 12:38:54 2000
Posted By: Sidney Chivers, , Nuclear Engineering, retired
Area of science: Engineering
ID: 975440395.Eg
Message:

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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