Every transparent material can be characterized by what is called its index of refraction,Ā n, given by the equation
HereĀ cĀ is the speed of light in a vacuum andĀ vĀ is the speed of light in the transparent material. Although normal air is not quite a vacuum, its density is small enough thatĀ vair is approximately equal toĀ c, so that we may takeĀ without too much error.
The precise mathematical relationship between the angles of incidence and refraction is given by what is known as Snellās law,
whereĀ n1 andĀ A1 are the index of refraction and the angle between the light ray and the normal, respectively, in medium 1, andĀ n2 andĀ A2 are the corresponding quantities for medium 2.
(a) Using the information in Table 9.1, compute the index of refraction for water and for fused silica (glass).
(b) Verify the result in Example 9.2 using Snellās law explicitly. Show, using the same relationship, that the values for the angles of refraction in air (medium 2) in panels (b), (c), (d), and (e) of Figure 9.36 are correct for the given angles of incidence in glass (medium 1).
Ā