Light as a Ray

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Light travels in straight lines, except when it doesn't. Having seen a shadow cast by some solid object, rectilinear propagation (read: definition of a straight line path) seems logical. But the behavior of light becomes the focus of some attention (get used to it) when we observe those instances when it is forced out of a straight line path. We engage two of these phenomena, reflection and refraction, every day. Knowledge of these optical phenomena will cause you to understand how light behaves in your every day coming and going. For example, we see most of the objects around us because light leaves some source, reflects off an object, and enters the eye.The reflection is not random but rather is well understood. Light entering the eye is directed to the retina by a phenomenon called refraction. The retinal image is then coded as electrical signals sent to the brain for processing. What you will encounter in these lessons are text pages, web sites, and in-class activities that will cause you understand the behavior of light when it is reflected and refracted. An attempt has been made to separate consideration of these two phenomena, although some web sites readily combine them. We will consider these early sites as they apply to reflection and revisit them when we encounter refraction.

 EAssuming that

 Light is a Ray

 allows us a useful  mechanism

by which  we explore these topics
  '...the Shadow knows."
  Pinhole cameras
 Speed of light
  Optical instruments
  The human eye
  Optical Illusions

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This page was last modified by mgosselin on 10/08/2005