Every transparent material can be characterized by what is called its index of refraction, n, given by the equation
Here c is the speed of light in a vacuum and v is the speed of light in the transparent material. Although normal air is not quite a vacuum, its density is small enough that vair is approximately equal to c, so that we may take without too much error. The precise mathematical relationship between the angles of incidence and refraction is given by what is known as Snell’s law,
where n1 and A1 are the index of refraction and the angle between the light ray and the normal, respectively, in medium 1, and n2 and 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 Snell’s 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).
5) A light ray incident on a block of glass makes an incident angle of 50.0° with the normal to the surface. The refracted ray in the block makes a 26.8° with the normal. What is the index of refraction of the glass?
6)
A light ray traveling from a higher index of refraction medium into a lower index of refraction medium (for example, from water into the air) would bend away from the normal to the medium surface. When the refracted ray is parallel to the boundary of the medium, θ2= 90°. The incident angle, θ1, becomes θc, called the
without too much error.
