1. Electromagnetic Spectrum

2. The Electromagnetic Spectrum

3. Electromagnetic Spectrum These are waves of electrical energy and unlike sound waves, they can travel through space; they do not need a medium to travel through. The wavelength is the distance between the crest of one wave and the crest of another wave. As you move to the right of the spectrum, what happens to the wavelength?

4. Gamma Rays Very high energy and high frequency rays Used in radiotherapy to treat cancer, by destroying cancer cells Sterilization of medical instruments (like before surgery)

5. X Rays High frequency, short wavelength rays Your doctor uses them to look at your bones Your dentist uses them to look at your teeth to detect cavities

6. Ultraviolet Rays Medium frequency and medium wavelength rays The sun emits these rays (UV rays)- this is what causes our skin to burn, and long term exposure can lead to premature aging of the skin Hot gases in the universe also emit UV rays

7. Infrared Rays Used by doctors to treat skin diseases and relieve the pain of sore muscles; in these treatments, the infrared rays pass through the patient’s skin and produce heat Photographers use it to take pictures in places where there is no visible light Burglar alarms also use infrared

8. Radio Waves These rays have the longest wavelengths in the EM spectrum Used to carry signals for your television and cellular phones Also used, obviously as their name implies, to bring music to your radio

9. Visible Light - Makes up on a very small portion of the electromagnetic spectrum -It is the only portion of the electromagnetic spectrum that we can see. -If you were to shine white light through a prism, it would produce rainbow colors

10. The colors we see are just different wavelengths of visible light

11. Behavior of Light Light can be: reflected refracted absorbed

12. Reflection –when light rays bounce off an object; this is how we see objects

13. Refraction Sometimes light rays bend, or change directions, like when they enter a new medium For example, light rays change directions when they move from air to water

14. Refraction This is why a pencil positioned at an angle in a glass of water looks bent. Light slows down when it enters a new medium, in this case water, and so it bends slightly making the pencil appear as if it is bent.