1. Electromagnetic Spectrum

2. Radiowaves
Wavelength from a few meters to 1 x 106m (further than distance from Earth to moon
Radio, TV, regulated by the FCC (Federal communications commission to reduce interference
AM Radio waves have a longer wavelength (lower frequency)
FM Radio waves have a shorter wavelength (higher frequency)

3. Microwaves Used to heat food because:
Water and fat absorb energy carried by microwaves
When these molecules move around faster, they get hotter
Microwaves are absorbed by molecules up to 2 cm below the surface
Used in radar because it penetrates rain and fog
Cell phones
“Quiet” because it is not made in nature
primarily made by man-made communication technology
SETI = Search for extraterrestrial Intelligence uses this frequency to search, because it is not made naturally

4. Infrared waves Examples of Infrared waves: TV's remote control
Sunlight
Fire
Radiators
The temperature-sensitive nerve endings in our skin can detect the difference between inside body temperature and outside skin temperature.
Infrared film to photograph a house to reveal areas in the structure that are leaking and wasting heat
Infrared light is even used to heat food sometimes - special lamps that emit thermal infrared waves are often used in fast food restaurants!

5. Primary source of Infrared Radiation is heat or thermal radiation
Any object that has a temp. radiates in the infrared, even ice cubes
An object that isn’t hot enough to emit visible light will still emit I.R.
Ex. Charcoal that is hot but not burning will emit heat
How Infrared radiation is used:
Snakes in the ‘viper’ family have sensory “pits” that detect I.R., so they can detect warm-blooded prey
Infrared pictures can be taken using special cameras and film that detects differences in temperature
Once the pictures are taken, they assign different brightness or false colors to them to provide a picture our eyes can interpret

8. Visible Light
EM waves we can see!!! Telescope, microscope, ect… How we see

9. Ultraviolet Light Invisible to the human eye
Some insects, like bumblebees, can see them
Ozone absorbs highest energy UV light
UV Light is used:
In Tanning beds
To stimulate skin cells to produce vitamin D
To sterilize surgical equipment
In Food processing
UV Light can cause sunburns and eventually malignant melanomas

10. X-rays X-ray light tends to act more like a particle than a wave
X-ray detectors collect actual photons of X-ray light
X-rays were first observed and documented in 1895 by Wilhelm Conrad Roentgen, a German scientist
He found them quite by accident when experimenting with vacuum tubes.
Originate in nature deep in space in the hot nebulae of stars
Exploding stars like novaes and supernovaes, and blackholes emit x-rays
Also can be created by a machine like those for medical x-rays
a picture of a supernova remnant taken using x-rays
The Earth's atmosphere is thick enough that virtually no X-rays are able to penetrate from outer space all the way to the Earth's surface

11. bones and teeth are dense and absorb more X-rays then your skin does
silhouettes of your bones or teeth are left on the X-ray film while your skin appears transparent
When X-ray light shines on us, it goes through our skin, but allows shadows of our bones to be projected onto and captured by film
Metal absorbs even more X-rays - can you see the filling in the image of the tooth

12. Gamma-rays
Smallest wavelengths and the most energy of any other wave in the electromagnetic spectrum
Most energetic form of light and is produced by the hottest regions of the universe
These waves are generated by radioactive atoms and in nuclear explosions
They are produced by:
violent events as supernova explosions or the destruction of atoms
The decay of radioactive material in space
Neutron stars and pulsars, and black holes

13. Medical Uses:
Radioactive Tracers (put into a patients body and followed as it goes through)
A patient with lung problems can breathe in Xenon-133, a gas that emits gamma rays
A special camera is used to take pictures
The patient isn’t injured by the radiation because they quickly breath out all the gas
Radiotherapy
Treatment of cancer
Engineers use gamma rays to look for cracks in pipes and aircraft parts
Radioactive substances like Cobalt-60 and Caesium-137 emit gamma radiation