Final Exam: Refraction and Reflection
1. Refraction occurs when light crosses the boundary between one material and another material.
What is the primary cause for this refracting of light upon crossing a boundary?
2. The diagram below shows the path of a light ray as it travels through air, across the air-water
boundary, and through the water.
On the diagram, label
 the air-water boundary with a B
 the normal line with an N
 the incident ray with an I
 the refracted ray with an R
 the angle of incidence with a θi
 the angle of refraction with a θr
3. Calculate the speed of light in each material
Material
Index of Refraction
Sodium Chloride
1.54
Alcohol
1.329
Sapphire
1.80
Silicon
2.5
Speed of light in material (m/s)
4. Complete the table to describe what will happen to a light ray in as it travels from medium 1 to
medium 2.
Physics B
Medium 1
Medium 2
Sodium Chloride
Alcohol
Alcohol
Sapphire
Sapphire
Silicon
Silicon
Sodium Chloride
Light will travel
(faster or slower)
Spring 2014
Ray will bend
(toward or away)
from Normal
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Final Exam: Refraction and Reflection
5. Draw a straight line to indicate the direction the spear fisherman should aim to spear the fish.
(Note: the picture represents the fishes image to the fisherman)
6. Which is more optically dense, Medium 1 or Medium 2?
Physics B
Spring 2014
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Final Exam: Refraction and Reflection
7. Assume you have a tank of water that contains a smaller tank of air. Using the incident ray
complete the path the light will travel as it goes through the air and back out the water. This
will be two sets of diagrams: 1) as the ray enters the air from the water and 2) as the ray exits
the air and enters the water. Label each incident ray, incident
8. Determine the image distance and image height for an 8cm tall object placed 48cm from the
converging lens having a focal of 36cm.
9. A magnified, inverted image is located 16cm from a converging lens, with a focal length of 6cm.
Determine the object distance and if the image is real or virtual.
Physics B
Spring 2014
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Final Exam: Refraction and Reflection
10. A concave makeup mirror is designed so that a person 25cm in front of it sees an upright image
at a distance of 50cm behind the mirror. What is the magnification of the image? Is the image
real or virtual?
11. An incident angle of a ray in air (n=1.0) is approaching the boundary with an unknown material
at an angle of incidence of 61.6°. The angle of refraction is 41.4°. Determine the index of
refraction of the unknown material. Using the index of refraction table provided, what material
is this most like?
Complete the following blanks by answering questions 12 and 13:
The critical angle is the angle of (#12) that causes light to (#13).
12. Referring to the statement above:
a. incidence b. refraction c. reflection
13. Referring to the statement above:
a. cross the boundary without refracting
b. undergo refraction at the same angle as the angle of incidence
c. refract at an angle of refraction of 90 degrees
d. reflect at the same angle as the angle of incidence
Physics B
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Final Exam: Refraction and Reflection
The next three questions focus on the brightness of the reflected and refracted rays and the
dependency of the brightness upon the angle of incidence.
14. Consider the diagram at the right for rays A,B, C,
and D incident upon a water-air boundary. The
corresponding refracted rays are shown. Draw the
corresponding reflected rays and
label them as A'', B'', C'', and D''.
15. As the angle of incidence is gradually increased, more and more of the energy from the incident
ray goes into the reflected ray, while less and less of the energy goes into the refracted ray.
Based on this fact, which one of the refracted rays in the diagram would be brightest and which
one would be dimmest?
Brightest:
Dimmest:
16. For incident ray C, the angle of refraction is 90°. The refracted ray C has the smallest amount of
energy of any refracted ray. Thus, it would be an extremely "dim" light ray. What is the angle of
incidence for ray C called?
17. Converging lenses are _____ at the center and _____ at the edges.
a. thickest, thinnest b. thinnest, thickest
18. Diverging lenses are _____ at the center and _____ at the edges.
a. thickest, thinnest b. thinnest, thickest
Consider the diagram at the right in answering the next two questions.
19. List the letters of all the converging lenses.
20. List the letters of all the diverging lenses.
21. Converging lenses will have ____________________ (positive, negative) focal lengths.
22. Diverging lenses will have ____________________ (positive, negative) focal lengths.
Physics B
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Final Exam: Refraction and Reflection
23. Case 1: If the object is located beyond 2F:
Description of Image Location
Upright or Inverted, Magnified or Reduced, Real or Virtual
24. Case 2: If the object is located at 2F:
Description of Image Location
Virtual
Upright or Inverted, Magnified or Reduced, Real or
25. Case 3: If the object is located between 2F and F:
Description of Image Location:
Virtual
Physics B
Upright or Inverted, Magnified or Reduced, Real or
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Final Exam: Refraction and Reflection
26. Case 4: If the object is located at F:
No Description Required
27. Case 5: If the object is located between F and the lens:
Description of Image: Location:
Upright or Inverted, Magnified or Reduced, Real or Virtual
Physics B
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