Graphics Programs Reference
In-Depth Information
How light behaves
The need and desire to understand just what light really is and how it works has been
the motivation behind questions and research that have been going on for many cen-
turies now. It wasn't until the late seventeenth century, however, that these questions
and the research work they fuelled started to yield results. They brought to the fore-
front theories and experiments that have since come to form the foundation of our
current understanding regarding the nature and workings of light.
In 1690, Dutch mathematician and astronomer
Christiaan Huygens
put forward the
proposal that light was made up of undulating waves that stimulated vision upon
reaching the eye. His idea was that light behaved in pretty much the same manner as
sound waves, which stimulate hearing upon reaching the ear.
English physicist
Sir Isaac Newton
, however, had been applying his own thinking to
the questions surrounding the workings of light and didn't agree with Huygens. So,
Newton proposed a different theory, one that described light as particles or rays that
travel in straight lines, bouncing or reflecting as they come into contact with solid mat-
ter. Indeed, research had already proven that light can be seen to travel in straight
lines; the simple example of reflections in a mirror had demonstrated that fact.
Learning about light - exercise one
To see just what Newton was basing his theory on, stand directly in front of a mirror
and take a look over your shoulder. What you see is the product of light travelling in
a straight line, giving you the ability to see whatever is directly behind you. Now, take
one step to your right. You will see that the reflection in the mirror is no longer of the
objects that are behind you, but rather ones that are away to the left-hand side of the
mirror itself. This trick of light is seen because the angle of light reflection is always
equal to and the opposite of the angle of incidence, often referred to as the viewing
angle.
See the following diagram:
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