Light and the Electromagnetic Spectrum Chapter 4.3 Light and the Electromagnetic Spectrum

Waves are everywhere! We are surrounded…. …by waves of radiation. Some we can see, such as visible light Some we cannot see such as radio waves As light leaves the sun, it spreads out Radiant energy is energy that travels in the form of radiation There are many forms of radiation

Electromagnetic Radiation In a light wave, electrical and magnetic fields vibrate Therefore, we call light “electromagnetic” radiation There is a spectrum called the electromagnetic spectrum: It includes visible light and other types of invisible radiant energy

Electromagnetic Radiation All forms of electromagnetic radiation travel as waves They range from long to short wavelengths (and high to low frequency)

1. Radio Waves Radio waves have the longest wavelength They are the lowest energy and lowest frequency waves

Uses of Radio Waves Radio and tv broadcasting Cellular phones Testing for illness (MRI – magnetic resonance imaging) Radar Microwaves

2. Microwaves A type of radio wave Microwaves have the shortest wavelength and the highest frequency of radio waves Microwave ovens use a specific wavelength of microwave

Uses of Microwaves Uses: Microwave ovens Telecommunications (satellites) Radar (tracking objects, weather forecasting) A microwave communication tower in Munich, Germany →

3. Infrared Waves These waves have a longer wavelength than visible light (lower frequency). Infrared waves are around us everyday! Also known as “heat radiation” Warm objects emit more infrared radiation than cooler objects Used with night goggles and in airports to see if passengers have a fever!

Uses of Infrared Waves Uses: Heat lamps (keep food warm) Remote controls Computers (to read CD-ROMs) Used with satellites to detect forest fires

4. Visible Light Visible light is electromagnetic radiation at a wavelength and frequency that we can detect with our eyes. It lies around the middle of the spectrum…

5. Ultraviolet Waves Just beyond the end of the visible region of the spectrum are UV waves Have a shorter wavelength and higher frequency than visible light

5. Ultraviolet Waves When UV light hits your skin, it allows you to make vitamin D (important for healthy bones and teeth) Too much UV exposure can cause damage

Uses of UV Waves Flourescent materials such as powder for fingerprints (absorb UV and emit visible light) Destroy bacteria in food and water Insect vision (butterflies)

6. X Rays Much higher energy (frequency) and shorter wavelength than UV waves Often used in medical field to take X ray photographs of bones and teeth

Uses of X Rays Images of organs, bones and teeth Airport security (x-ray screening of baggage) Inspect for cracks in engines of jets

7. Gamma Rays The highest energy waves in the spectrum Shortest wavelength and highest frequency Produced from nuclear reactions Used in specific burst to kill cancer cells.