Chapter 17 - Reflection
1. What is meant by the normal to a surface?
2. Define the law of reflection (be sure to include the terms “angle
of incidence” and “angle of reflection”).
3. Does the law of reflection still hold true for diffuse reflection?
Explain your answer (diagrams will help).
4. Compare the angle of incidence with the angle of refraction when
a light ray passes from air into glass at a non-zero angle.
5. What are the units for the index of refraction?
6. What is the “critical angle” of incidence?
7. What happens to a ray of light with an angle of incidence greater
than the critical angle?
8. List the different colors of light in order of increasing
9. A dry road is a diffuse reflector, while a wet road is not. Sketch
a car with headlights illuminating the road ahead for each situation (2
diagrams). Using light rays, show on your diagrams why the wet road
would appear darker to the driver than the dry road.
10. Explain why it is desirable that the pages of a book be rough rather
than smooth and glossy.
11. For this problem, assume that the angle of incidence always remains
the same. What happens to the angle of refraction as the index of
12. Which color of light travels fastest in glass: red, green, or blue?
For problems 13-22, draw small (hand sketched)
ray diagrams in addition to showing all calculations.
13. A ray of light strikes a mirror at an angle of 53º to the normal.
a. What is the angle of reflection?
14. A ray of light makes an angle of 36º to the mirror’s surface
(not the normal).
b. What is the angle between the incident ray and the reflected
a. What is the angle of incidence?
15. A ray of light has an angle of incidence of 30.0º on a block of
quartz and an angle of refraction of 20.0º. What is the index
of refraction for this block of quartz?
b. What is the angle between the angle of incidence and
the angle of reflection?
16. A ray of light travels from air into a liquid. The ray is
incident upon the liquid at an angle of 30.0º. The angle of
refraction is 22.0º.
a. What is the index of refraction of the liquid?
17. A ray of light is incident at an angle of 60.0º upon the surface
of a piece of crown glass. What is the angle of refraction?
b. Using the reference tables, what liquid could this possibly
be? (Choose the closest liquid)
18. A ray of light strikes the surface of a pond at an angle of incidence
of 36.0º. At what angle is the ray refracted?
19. Light is incident at an angle of 60.0º on the surface of a
diamond. Find the angle of refraction.
20. A ray of light has an angle of incidence of 33.0º in crown
glass. What is the angle of refraction when the light re-emerges
into the air?
21. A ray of light passes from water into crown glass at an
angle of 23.2º. Find the angle of refraction.
22. Light goes from flint glass into corn oil. The angle of refraction
in the corn oil is 25º. What is the angle of incidence in the
23. What is the speed of light in diamond?
24. The speed of light in chloroform is 1.99 x 108 m/s. What
is its index of refraction?
25. Find the critical angle for diamond.
26. A ray of light in a tank of water has an angle of incidence of
55º. What is the angle of refraction in air?
27. Although the light coming from the sun is refracted while passing
through Earth’s atmosphere, the light is not separated into its spectrum.
What does this tell us about the speeds of different colors of light while
traveling through air?
28. Neatly copy the diagram below over on your paper (the exact size
is not important, but bigger diagrams are more accurate). The ray
of light passes through a block of crown glass.
a. Calculate the angle of refraction inside the glass.
b. Calculate the angle of refraction as it re-emerges into
c. How does this compare with the angle of incidence?
d. Using a protractor & ruler, trace the complete path
of the ray through the glass.