What is an electromagnetic wave? Electromagnetic waves travel as vibrations in electric and magnetic fields. Electromagnetic waves are waves that have some electrical properties and some magnetic properties. An electric field is a region in which particles are pushed or pulled. Wherever there is electric charge there is an electric field. A moving electric charge (electron) is called electric current.

Continued When the electric field changes, so does the magnetic field. A change in the magnetic field causes a change in the electric field. When one field changes, so does the other, this results in what scientists call an electromagnetic wave.

Wavelength and Frequency Wavelength is the distance from crest to crest of a wave or trough to trough. Frequency is the number of waves that occur in a given amount of time. (measured in 1/sec, per second). http://phet.colorado.edu/simulations/sims.php?sim=Wave_on_a_String

How do we read this?

Try a few examples on the Elmo!

Radio Waves The longest wavelength in the entire spectrum. Can be compared to the size of a football field. Carry signals to your T.V., Radio and Cellular Phone. http://science.hq.nasa.gov/kids/imagers/ems/radio.html

Microwaves Compared to the size of a bumble bee and measured in centimeters. Used to cook food at home and are used to transmit information because of their ability to penetrate haze, light rain, snow, clouds and smoke. http://science.hq.nasa.gov/kids/imagers/ems/micro.html

Infrared Compared to the size of a cell or bacteria. When thinking of infrared light, we think of heat. Infrared light is also used in T.V. remotes. http://science.hq.nasa.gov/kids/imagers/ems/infrared.html

Visible Light These are all the electromagnetic waves that we can see. They appear to us in the form of colors. What are the primary colors? http://science.hq.nasa.gov/kids/imagers/ems/visible.html

Ultraviolet Light When we think of ultraviolet light, we want to think of microscopic organisms like viruses (smaller than cells or bacteria). Ultraviolet light is responsible for sunburns. http://science.hq.nasa.gov/kids/imagers/ems/uv.html

X- Rays These are the size of atoms. Has anyone ever had an x-ray? Does it penetrate through your entire body? http://science.hq.nasa.gov/kids/imagers/ems/xrays.html

Gamma- Rays They have the shortest wavelength and are produced by the hottest regions of the universe. They are produced during supernova explosions, the destruction of atoms and the decay of radioactive materials. http://science.hq.nasa.gov/kids/imagers/ems/gamma.html