1. Light and the Electromagnetic Spectrum
Chapter 4.3
Light and the Electromagnetic Spectrum

2. 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

3. 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

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

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

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

7. 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

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

9. 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!

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

11. 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…

12. 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

13. 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

14. 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)

16. 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

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

18. 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.