What are radio waves?
Exhibit #1 Concept: A moving charge like a spark produces EM radiation This exhibit will use a spark plug, receiver and spectrum analyzer to approximate Hertz’s experiment in which he discovered radio waves. A spark plug is set up to give off a spark when the visitor pushes a button. A receiver positioned at some distance away will audibly register the signal. The spectrum analyzer will show spikes occurring at many different frequencies indicating radio emission. Spark plugs are a source of man-made radio waves which interfere with the radio telescopes at NRAO. We prohibit most vehicles with spark plugs from driving on the site. Because this exhibit could really cause interference at the telescopes, the exhibit will have to be shielded in a Faraday cage. Thus, this exhibit can be used to teach visitors that interference is important and needs to be controlled at the NRAO. Outcome: An accelerated charge like a spark from a spark plug produces radio waves. Radio waves cannot pass throug
Electromagnetic radiation is a wave that combines electric and magnetic fields, moving out from its source as an expanding sphere and having waves as the feilds alternate in value. Its formal name is Transverse Electro Magnetic wave, or TEM. This kind of radiation has different utility as its wavelength changes. Waves of a very long wavelength, such as thousands of meters, tend to travel along the surface of the earth and even penetrate into the water. These are useful for communication with submarines, and for broadcasting time signals. Broadcast radio, short-wave radio, television, cellular telephones, walky-talkies, 2-way police radios, satellite television, and other such communication/broadcast systems all use electromagnetic radiation, or “Radio Frequency Waves”. Each communication service uses a part of the spectrum that is suitable for its needs. Light, infra-red heat, ultra-violet (black light), and even X-rays and Gamma-rays are all forms of electromagnetic waves. All of thes
