What is an electromagnetic wave Electromagnetic waves travel

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What is an electromagnetic wave? • Electromagnetic waves travel as vibrations in electric and

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

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

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?

How do we read this?

Try a few examples on the Elmo!

Try a few examples on the Elmo!

Radio Waves • The longest wavelength in the entire spectrum. • Can be compared

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/ra dio. html

Microwaves • Compared to the size of a bumble bee and measured in centimeters.

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/mi cro. html

Infrared • Compared to the size of a cell or bacteria. • When thinking

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

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

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

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

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