Elenco Fiber Optics Voice and Data Kit - Manual (Page 10)

REFRACTION
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Figure 2B
Refraction
Red
Orange
Yellow
Green
Blue
Violet
Refraction
White Light
The speed of light can be defined as the velocity of
electromagnetic energy in a vacuum such as space.
The speed of light will vary as it travels from one
material to another, which, because of wave motion,
results in light changing its direction. This change of
direction of light is called refraction. In addition,
different wavelengths of light travel at different
speeds in the same material. The best example of refraction if the prism of
Figure 2B. White light entering the prism contains
all colors. The prism refracts the light and changes
speed as it enters the prism. Because each color or
frequency changes speed differently, each is
refracted differently. Red light deviates the least and
travels the fastest, while violet light deviates the
most and travels the slowest. The white light then
emerges from the prism divided into the colors of
the rainbow.
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REFRACTIVE INDEX
One of the important measures that you often come
across in light is refractive index. The refractive
index can be defined as the ratio of the speed of
light in a vacuum to the speed of light in a material.
n = c(vacuum) / c(material)
where: n is the refractive index
c is the speed of light
Since the speed of light in a vacuum is always faster
that the speed of light in any material, the refractive
index is always greater than one. The amount that a
ray of light is refracted depends on the refractive
index of the two materials.
5 The above paragraphs are reproduced by permission TECHNICIAN’S GUIDE TO FIBER OPTICS 2E (PAGES 36, 37)
By Donald J Sterling, Jr. - DELMAR PUBLISHERS, INC., Albany, New York, Copyright 1993