In the figure below light travels from material a through th

In the figure below, light travels from material a, through three layers of other materials with surfaces parallel to one another, and then back into another layer of material a. The refractions (but not the associated reflections) at the surfaces are shown.

a) In which material is the speed of light the greatest?

b) In which material is the speed of light the least?

Solution

The greater the angle of refraction, the closer to the direction of the normal the light will travel; so index of refraction is in the order of

n_d>n_b>n_a>n_c

Since speed of light

v=c/n

where n=index of refraction

a)

speed of light the greatest for material c since it has smaller index of refraction compared to the other

_b)

speed of light the greatest for material d since it has largerr index of refraction compared to the other