Electromagnetic
Spectrum
Introduction
!  Electromagnetic waves are transverse waves that do not
require matter to carry energy.
!  These waves make up the Electromagnetic (EM) Spectrum.
!  The EM Spectrum is the range of all possible frequencies of
electromagnetic radiation.
!  The EM Spectrum extends from radio waves with low
frequencies and long wavelengths to gamma radiation
waves with high frequency and short wavelengths.
!  The EM spectrum covers wavelengths from thousands of
kilometers down to a fraction of the size of an atom.
Types of Waves
!  Radio: Your radio captures radio waves emitted by radio
stations, bringing your favorite tunes. Radio waves are
also emitted by stars and gases in space. These waves
have the longest wavelength and lowest energy.
!  Microwave: Microwave radiation will cook your popcorn
in just a few minutes, but is also used by astronomers to
learn about the structure of nearby galaxies.
!  Infrared: Night vision goggles pick up the infrared light
emitted by our skin and objects with heat. In space,
infrared light helps us map the dust between stars.
Types of Waves (cont.)
!  Visible: Our eyes detect visible light. Fireflies, light bulbs, and
stars all emit visible light. Red is the lowest frequency, violet is
the highest frequency (ROY G BIV)
!  Ultraviolet: Ultraviolet radiation is emitted by the Sun and are
the reason skin tans and burns. "Hot" objects in space emit
UV radiation as well. These waves can be harmful.
!  X-ray: A dentist uses X-rays to image your teeth, and airport
security uses them to see through your bag. Hot gases in the
universe also emit X-rays. These waves can be harmful.
!  Gamma ray: Doctors use gamma-ray imaging to see inside
your body. The biggest gamma-ray generator of all is the
Universe. These waves have the shortest wavelength and
highest energy. These waves can be harmful.
How do we measure the properties of light?
!  A Spectrometer is an instrument used to measure
properties of light over a specific portion of the EM
Spectrum.
!  used
to identify materials by measuring the lights intensity
!  used to measure wavelengths that range from Radio to
Gamma
!  Has been used to identify minerals on Mars.
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