1. Lesson P2 – The Electromagnetic Spectrum
Unit 3 ~ physics
Lesson P2 –
The Electromagnetic Spectrum

2. Beyond Visible Light
Light radiates from the Sun and other stars in all directions.
Energy, such as light, that travels by radiation is often called radiant energy.
In addition to the visible energy that we call light, the Sun also radiates invisible energy.

3. Electromagnetic Radiation
In water waves, water particles vibrate up and down as the wave passes through the water.
In a light wave, electrical and magnetic fields vibrate, so light is classified as electromagnetic radiation.
Electromagnetic radiation is the transmission of energy in the form of waves.

4. Electromagnetic spectrum
The electromagnetic spectrum is made up of the visible light energy and all the invisible forms of radiant energy.

5. Wavelengths longer than visible light
Radio waves: AM & FM radio, TV, MRI
Microwaves: microwave ovens, radar
Only foods that contain water particles can be heated using microwaves.
Infrared waves: remote control, computer reading a CD-ROM
Also known as heat radiation.

6. Wavelengths Shorter than visible light
Ultraviolet waves: kills bacteria in food, water, & medical supplies; absorbed by fluorescent materials (used by police to study fingerprints)
Enables your body to make Vitamin D, overexposure can result in sunburns, skin cancers, & damage to the surface of the eye.

7. Wavelengths Shorter than visible light
X-Rays: photograph teeth, bones, luggage, and inside of machines
Gamma Rays: kills cancer cells in radiation therapy