Radiant Energy:Light
The Propagation of Light:Scattering
Refraction
Refraction is the change in direction of light due to a change in its speed.
The index of refraction, n, quantifies how much a medium slows the speed of light.
(10) 
(11) 
Example 3
How long does it take for light to travel 2.50 m in water?
Example 4
A beam of light enters (a) water or (b) glass (n = 1.50) at an angle of 60.0° relative to the normal. Find the angle of refraction for each case.
Example 5
One night, while on vacation in the Caribbean, you walk to the end of a dock and, for no particular reason, shine your laser pointer into the water. When you shine the beam of light on the water a horizontal distance of 2.4 m from the dock, you see a glint of light from a shiny object on the sandy bottom–perhaps a gold doubloon. If the pointer is 1.8 m above the surface of the water, and the water is 5.5 m deep, what is the horizontal distance from the end of the dock to the shiny object?
To find the wavelength of light in a given medium:
(12) 
Where 
is
the wavelength in a vacuum.
Total Internal Reflection
Total
Internal Reflection – When
light in a medium in which its speed is relatively low encounters a
medium in which its speed is greater, the light will be totally reflected
back into its original medium if its angle of incidence exceeds the
critical angle, 
,
given by:
(13) 
Example 6
Find the critical angle for light traveling from glass (n = 1.50) to (a) air and (b) water.
Color
Primary Colors
Colored light (Additive)
Yellow Stained glass
Pigments (Subtractive)
