Chapter 13: Electromagnetic Waves

Section 2: The Electromagnetic Spectrum The entire range of electromagnetic wave frequencies is called the electromagnetic spectrum. http://www.youtube.com/watch?v=bjOGNVH3D4Y

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B. Radio waves: low-frequency electromagnetic waves with wavelengths from less than a centimeter to about 1000 meters. 1. Microwaves: radio wavelengths of about 1 to 10 cm.

Radar: radio waves bounced off an object to determine its speed and location Magnetic Resonance Imaging (MRI): radio waves produce an image of the inside of the body

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C. Infrared waves: electromagnetic waves with a slightly higher frequency than radio waves; people feel it as thermal energy or warmth D. Visible light: has wavelengths between about 390 to 770 billionth of a meter; can be seen with the eye

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Ultraviolet waves: have frequencies slightly higher than visible light; can damage skin Ultraviolet waves can kill bacteria. Ultraviolet waves can be absorbed by some fluorescent materials and released as visible light.

Ozone layer above Earth’s surface absorbs most of the Sun’s harmful ultraviolet waves.

F. X rays and gamma rays: ultra-high-frequency EM waves that can travel through matter, break molecular bonds, and damage cells

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1. X rays are used to provide images of bones and to examine suitcases at airports without opening them. Radiation therapy is used to kill diseased cells. Gamma rays are emitted by radioactive sources (uranium, plutonium, etc.)