Refraction Action

1. Refraction Action An adventure in light and optics Scott Hopkins and Matt Aufman NSF North Mississippi GK-8 University of Mississippi February 2006 NSF North Mississippi GK-8

2. Optics & Refraction Optics is the scientific study of light and how it interacts with different media. Refraction is the bending that occurs to light as it passes through different media. NSF North Mississippi GK-8

3. Crest Trough Nature of Light Light travels at a speed of 299,792,458 meters per second. That’s equal to 186,000 miles per second! Light moves in a wave-like motion. The top of the wave is called the crest, and the bottom of the wave is called the trough. NSF North Mississippi GK-8

4. Wavelength Amplitude Wave Characteristics Wavelength - The distance from crest to crest or trough to trough. The color of light is determined by the wavelength. Wavelength is measured in nanometers (1 / 1,000,000,000 meter). Red light has the longest wavelength,and violet light has the shortest wavelength. Amplitude - The height or depth of a wave. The brightness of light is determined by the amplitude of the wave. The higher the amplitude, the brighter the light. NSF North Mississippi GK-8

5. Tyndall Effect An Irish Scientist named John Tyndall discovered that light bounced off of tiny particles in the air and in liquids. This scattering of light became known as the Tyndall Effect What are some things that may cause light to scatter in a liquid? NSF North Mississippi GK-8

6. The Mississippi River The Mississippi River carries Particles from many different Sources: Mud Silt Microorganisms Fish Plants Pollution How does this relate to the Tyndall Effect? http://www.photohome.com/pictures/missouri-pictures/mississippi-river-1a.jpg NSF North Mississippi GK-8

7. Lenses There are two main types of lenses: Convex lenses and Concave lenses Convex lenses are thin around the edges and bulge outward at the center on both sides of the lens. Convex lenses magnify objects. Concave lenses are thick around the edges and thin at the center of the lens. Concave lenses minimize objects. NSF North Mississippi GK-8

8. Lenses and Light When light travels through air, it travels at a constant speed in parallel lines. Light bends as it passes through different media. NSF North Mississippi GK-8

9. Lenses and Light When light passes through a concave lens, the rays are bent away from each other. NSF North Mississippi GK-8

10. focal point focal length Lenses and Light Convex lenses bend light rays toward each other. The point at which the light waves cross is called the focal point. The distance from the lens to the focal point is called the focal length (measured in centimeters). NSF North Mississippi GK-8

11. focal length =100 cm Lens Power The refractive power of a lens is measured in Diopters. A Diopter is equal to 1 divided by the focal length. Example: What is the refractive power of a lens with a focal length of 100 centimeters? 100 centimeters = 1 meter Diopter ? = 1 ÷ focal length Diopter ? = 1 ÷ 1 meter 1 Diopter NSF North Mississippi GK-8

12. What Questions Do You Have? NSF North Mississippi GK-8

13. Sources University of Indiana. No date of publication given. The Tyndall Effect. Accessed 28 June 2005. http://chemlearn.chem.indiana.edu/demos/Tyndall.htm University of Tennessee Department of Physics and Astronomy. Astronomy 162: The Electromagnetic Spectrum. Accessed 18 December 2005. http://csep10.phys.utk.edu/astr162/lect/light/spectrum.html Wikipedia the Free Encyclopedia: Tyndall Effect. Accessed 28 June 2005. http://en.wikipedia.org/wiki/Tyndall_effect Wikipedia the Free Encyclopedia: Refraction. Accessed 22 May 2005. http://en.wikipedia.org/wiki/Refraction Wikipedia the Free Encyclopedia: Electromagnetic Spectrum. Accessed 23 May 2005. http://en.wikipedia.org/wiki/Electromagnetic_spectrum NSF North Mississippi GK-8