exploring-light-and-color-light-and-color- video.htmhttp://videos.howstuffworks.com/hsw/9942- exploring-light-and-color-light-and-color- video.htm 6 minutes, good intro

 The electromagnetic spectrum is a series of radiation waves produced naturally by the sun

 Electromagnetic waves transport energy.  The higher the frequency the more dangerous the waves are to humans. ◦ Radio waves are low frequency and do not cause harm ◦ Gamma rays are high frequency and can cause genetic mutations

1. Radio waves- lowest frequency ◦ E.g. Radio and television signals 2. Micro-waves- ◦ E.g. From satellites, cell phones, internet, micro-wave ovens

3. Infrared- just below the visible spectrum  Felt as heat emitted by objects that are warmer than their environment ◦ E.g. Heat lamps used in incubators 4. Visible Light-seen by humans  White light is a result of a combination of different wavelengths. These can be separated with a prism or with water droplets.

5. Ultraviolet rays- frequency just above the visible spectrum  In small amounts = tan,  In large amounts = burn or skin cancer 6. X-Rays- very short rays  can penetrate skin and muscles but are absorbed by bone  Must limit exposure

7. Gamma Rays- the shortest rays and the highest energy  From nuclear reactions  Cause genetic mutations and cancer  Used in radiotherapy to target cancer cells (ironic)

 Light travels in a straight line  As it encounters objects the path of the light can change  When light hits an object some of the light is partially absorbed by the object

 Rays of light are reflected when they rebound off the object.

1. The incoming and outgoing light are in the same plane 2. The angle of reflection is equal to the angle of incidence (angle that comes in)

 Refraction is when the light is bent as it travels through a medium of different density  Show gizmo

Light exits into medium (air) of lower index of refraction, and turns left.

 A lens is a curved transparent substance used to bend light rays

 Convergent lenses bring light together to focus the light on one spot  Used to correct hyperopia (far sightedness)

 Divergent lenses spread light apart  Used to correct myopia (near sightedness)