Electromagnetic waves are types of radiation, or energy that redistributes itself as it travels. All electromagnetic waves travel at the speed of light. There are seven different types of electromagnetic waves in order of lowest to highest frequency they are Radio Waves, Microwaves, Infrared, Visible, Ultraviolet, X-rays and Gamma Rays. All of these waves have impact on our lives even if we don't realize it.
Radio Waves are the waves we use for radios, (duh) and TV. Radio Waves are the longest of the electromagnetic waves and thus have the lowest frequency. Radio waves were proved to exist by Henrich Hertz in the late 19th century and we now use the unit of frequency measurement the Hertz. Radio waves, however, are not just emitted here on earth, stars and planets emit them also. By studying the Radio waves stars emit with Radio telescopes people are able to learn much about the universe. Radio waves can be produced by any object with a changing magnetic field. Radio waves have wavelengths from 3X10^0meters to 8X10^6meters. While the frequencies vary from 6X10^2 Hz for the longer waves to 1X10^8Hz for the shortest waves. Modulation is the use of varying amplitudes or frequencies to prevent the signal from degrading this is how radio stations get information to us, for example FM stations use Frequency Modulation while AM stations use Amplitude Modulation.
Gamma Rays are the shortest type of electromagnetic waves and thus have the highest frequency. Gamma Rays occur with things that are sublime in nature such as nuclear explosions, lightning, and radioactive decay. Even though Gamma Rays are not common in our daily life they are more common in space. Gamma Rays in space are created by stars, supernovas, pulsars and black holes. Gamma Ray bursts which occur when some black holes are formed are the most energetic occurrences in the universe, they can energy in 10 seconds as our sun is predicted to in its 10 billion year life span. Amazing. Gamma Rays have frequencies greater than 10^19 Hz and wavelengths less than 8X10^-10 Meters. these wavess are used in radiation treatments for people to kill cancer cells but unmonitored exposeure to Gamma Rays can kill other types of cells as well.
Works Cited
http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html
http://lectureonline.cl.msu.edu/~mmp/applist/Spectrum/s.htm
http://missionscience.nasa.gov/ems/01_intro.html
http://school.discoveryeducation.com/lessonplans/interact/electromagneticspectrum.html
Images
http://startswithabang.com/wp-content/uploads/2009/01/swift-gamma-ray-lg.jpg
http://www.thepunkguy.com/music/antique_radios_25.jpg
