Optics
The science of making light go where we want it to is called optics.
From now on we will ignore the wavy character of light, and think of it as a stream of little bullets that travel in straight lines. We will represent the light coming from a source as a collection of lines representing the paths light takes, and we will call one of these lines a ray.

The simplest optical phenomenon is a shadow, in which some of the rays of light are blocked by an object. We get big shadows if the object is much closer to the light source than it is to the wall where the shadow appears.



 


Sally explains:"Shadows come about when you have a source of light, something for the light to bump into, and it helps to see them if there is some sort of screen or the ground behind the object where it casts an area of darkness. What's going on here is that light travels in straight lines. When light bumps into an object, it can't go around and so it just stops or bounces back. What's left behind the object is the area of darkness or less light -- which we call a shadow."

Fuzzy shadows and sharp shadows

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Copyright 2000 J. P. Straley and S. S. Kovash