Download Refraction Practice Problems

Refraction Practice Problems
AP Physics
Name:
Period:
1. Which of the following statements is true for the refraction of light as a wave crosses the boundary of two
different media.
a) The angle of refraction will generally be the same as the angle of incidence
b) The light wave will travel at lower speeds in the new medium than it did in the original medium
c) The light wave will be redirected closer to the normal line if it moves from a medium of high index of
refraction to a medium with a lower index of refraction (n1 > n2)
d) The light wave will be redirected closer to the normal line if it moves from a medium of high index of
refraction to a medium with a lower index of refraction (n1 > n2)
e) The light wave will be redirected further from the normal line if it moves from a medium of high index of
refraction to a medium with a lower index of refraction (n1 > n2)
2.
a)
b)
c)
Which of the following statements about index of refraction is accurate?
It is always greater than or equal to 1
It is inversely proportional to the speed of light in a medium
It is inversely proportional to the wavelength of the light in the medium
3.
a)
b)
c)
Consider a beam of light traveling from one medium to another.
Does its wavelength change?
Does its frequency change?
Does its speed change?
4. Which of the following statements is correct regarding the critical angle at the boundary between a medium
and the air around it?
a) The critical angle is independent of the wavelength of the light in the medium.
b) The critical angle is greater for a material with a smaller index of refraction.
c) The critical angle is greater for a material with a greater index of refraction.
d) The critical angle can be any angle up to 180°.
5. Explain why the pencil in the picture here appears almost severed.
6. The photos shown down the side of the page were taken with a camera mounted on
tripod at a fixed angle – this is clear because the plastic cup appears identical in all
images. In each photo, there is a penny on the bottom of the cup, up against the far edge,
but it is barely visible in the first picture. When water is poured into the container, you
see more of the coin. Why does the coin appear differently to you when you add water to
the cup?
7. The speed of light in one material is 2.07 x 108 m/s. What is the index of refraction of
that material?
8. A beam of light enters the top surface of the water with a 60° angle of incidence.
What will the angle of the refracted ray be?
9. Light passes from air into sapphire. If the angle of incidence is 20° what is the angle
of refraction?
10. A beam of light traveling in air is incident on a transparent plastic material at an
angle of 50°. The angle of refraction is 35°. What is the index of refraction of the plastic
material?
11. A beam of light in air is incident on the surface of a slab of fused quartz. Part of the beam is transmitted
into the quartz at an angle of refraction of 30° and part is reflected. What is the angle of reflection?
12. A He-Ne (helium-neon) laser beam (λ = 632.8 nm in air) is directed through ethyl alcohol. What are the
wavelength and frequency of the light in the alcohol?
13. A beam of light passes through at 45°-90°-45° prism and
undergoes total internal reflection, as shown in the diagram.
a) What can be said about the index of refraction of the prism?
b) What if this happened when the prism were underwater?
What can be said about the index of refraction of the prism,
then?
14. At what angle must a submerged diver in a lake look toward the surface to see the setting Sun?
15. A submerged diver shines a light toward the surface of the water at angles of incidence of 40° and 50°. Can
a person on the shore see a beam of light emerging from the surface in either case? Justify your answer
mathematically. If there is a visible beam, at what angle will the beam emerge from the lake?
16. To a submerged diver looking upward through the water, the altitude of the Sun appears to be 45°. What is
the Sun’s actual altitude? [Altitude means angle measured above the horizon.]
17. A light beam traveling upward in a plastic material with an index of refraction of 1.60 is incident at an
angle of 45° upon a horizontal upper air interface.
a) Is the beam transmitted? If so, at what angle?
b) Suppose the upper surface of the plastic material is covered with a layer of liquid with an index of refraction
of 1.20. What happens in this case? [Is the beam transmitted? If so, at what angle?]
18. Which of the following statements about dispersion are true?
a) Dispersion only occurs when the angle of incidence is 0.
b) Transparent materials have difference indices of refraction for different frequencies of light
c) Dispersion changes the frequency of a lightwave
19. When does dispersion occur?
20. A beam of red light is incident on an equilateral prism as shown in the diagram.
a) If the index of refraction for red light is 1.400, at what angle θ does the beam emerge from the other face of
the prism?
b) Suppose the incident beam were white light . What would be the angular separation of the red and blue
components in the emergent beam if the index of refraction for blue light is 1.403?
21. An inventor layers two slabs of different transparent materials with their top and bottom surfaces horizontal
as part of an optical system. The bottom layer has an index of refraction of ni = 2.0 and the top layer has an
index of refraction of n2 = 1.7. The top surface of the upper layer is exposed to the air.
a) Find the critical angle at which light will be reflected at the interface of the two materials.
b) Find the angle of incident to the junction between the two layers where light will pass through the interface
between the two materials and hit the top of upper layer at the critical angle.