The Electromagnetic Spectrum The Electromagnetic Spectrum EMS l

The Electromagnetic Spectrum Ø The Electromagnetic Spectrum (EMS) l l l l Radio Waves – longest waves, lowest energy. Microwaves Infrared Visible Light Ultraviolet Light X-Rays Gamma Rays – shortest waves, highest energy.

Electromagnetic waves u u u Energy carried by an electromagnetic wave is called radiant energy. Waves are formed when a charged particle vibrates. Most of the Earth’s radiant energy comes from the Sun. Electromagnetic waves can travel through empty space. Short wavelength = high energy. High frequency = high energy.

Radio Waves Longest Wavelength, lowest energy u Radio and Television u Digital transmission is clearer than analog. u A carrier wave carries sound or images. u Broadcasting = sends information in all direction u

Infrared Radiation • Infrared • Felt mainly as heat • Can make images of Earth.

Visible Light • Narrow range of wavelengths that we can see! – ROY G BIV • • Red Orange Yellow Green Blue Indigo Violet

Ultraviolet Radiation • Makes people tan • Causes sunburn and skin cancer • Mostly blocked by ozone layer. – Ozone layer is threatened by CFCs (Chlorofluorocarbons) that come from airconditioners, refrigerators, and foam packaging. q. Can be used to kill germs on medical tools. q 7% of sun’s energy comes as UV rays.

X-Rays u. A lot of energy. u Too many can cause cancer. u Pass through soft tissue but stopped by denser items. u Can be used to see broken bones. u Dentists use to detect cavities.

Gamma Rays l Most powerful l Highest frequency l Shortest wavelengths l Deadly in small amounts l Used to kill cancer cells l Also used in PET scans to track breakdown of a chemical tracer in your body.