Transcript Electromagnetic Spectrum

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/rad
io.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/mi
cro.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