•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)

•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

The temperature-sensitive nerve endings in our skin can detect the difference between inside body temperature and outside skin temperature.

Infrared light is even used to heat food sometimes - special lamps that emit thermal infrared waves are often used in fast food restaurants!

•Examples of Infrared waves:

TV's remote control

Sunlight

Fire

Radiators

Infrared film to photograph a house to reveal areas in the structure that are leaking and wasting heat

•Primary source of Infrared Radiation is heat or thermal radiationAny object that has a temp. radiates in the infrared, even ice cubesAn 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 preyInfrared 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

EM waves we can see!!! Telescope, microscope, ect… How we see

•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

•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.

•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

•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

•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

•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

•Engineers use gamma rays to look for cracks in pipes and aircraft parts

•Radioactive substances like Cobalt-60 and Caesium-137 emit gamma radiation

•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 raysA special camera is used to take picturesThe patient isn’t injured by the radiation because they quickly breath out all the gas

RadiotherapyTreatment of cancer