1. ELECTROMAGNETIC WAVES The Electromagnetic Spectrum
Chapter 12, Section 2 Notes
ELECTROMAGNETIC WAVES
The Electromagnetic Spectrum

2. Chapter 12 Main Idea: Electromagnetic waves can transfer energy through matter and space. Sec. 2 Main Idea: Each type of electromagnetic wave has a certain range of frequencies and wavelengths.

3. The entire range of electromagnetic wave frequencies is called the electromagnetic spectrum. See page 360.
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. See page GPS, Doppler Effect, etc.

4. Radar – radio waves bounced off an object to determine its speed and location. Law enforcement officers use radar to measure how fast a vehicle is moving.
Magnetic Resonance Imaging (MRI) – radio waves produce an image of the inside of the body.

5. Infrared waves – electromagnetic wave with a slightly higher frequency than radio waves; people feel it as thermal energy or warmth. They are used to control your television, read CDs, and form images to objects. See page 362.
Visible light – has wavelengths between about 390 t0 770 billionth of a meter; can be seen with the eye. (ROY G. BIV) If all colors are present, you see white.

6. Ultraviolet waves – have frequencies slightly higher than visible light; can damage skin.
1. Ultraviolet light can kill bacteria.
2. Ultraviolet light can be absorbed by some fluorescent materials and released as visible light. This is helpful in forensics. See page 363.
3. Ozone layer above Earth’s surface absorbs most of the Sun’s harmful ultraviolet waves.
CFCs can damage our ozone, which exposes us all to excess UV radiation. See page 364.

7. X rays and gamma rays – ultra-high-frequency electromagnetic waves that can travel through matter, break molecular bonds, and damage cells.
1. X rays are used to provide images of bones and to examine suitcases at airports without opening them.
2. Radiation therapy is used to kill diseased cells.