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Refraction Gizmo : ExploreLearning
ASSESSMENT QUESTIONS:
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Questions & Answers
1. In which image below is the angle of refraction the greatest?
A. Image A
B. Image B
C. Image C
D. Image D
Correct Answer: D. Image D
Explanation: The angle of refraction is the angle from the light ray in medium 2 to the
normal. Image D therefore shows the greatest angle of refraction, as well as the smallest
change of direction in the light ray. Because the light ray is not bent very much in image D,
the indexes of refraction of the two mediums must be very similar.
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2. If the angle of incidence increases and the indexes of refraction stay the same, what happens
to the angle of refraction?
A. the angle of refraction stays the same
B. the angle of refraction decreases
C. the angle of refraction increases
D. cannot be determined from the information provided
Correct Answer: C. the angle of refraction increases
Explanation: When the angle of incidence is 0 no refraction occurs at all, so the angle of
refraction is zero. As the angle of incidence increases, the angle of refraction increases as
well if all other variables are held constant.
3. Based on the image from the Gizmo below, which medium has a larger index of refraction?
A. Medium 1 has a larger index of refraction.
B. Medium 2 has a larger index of refraction.
C. Both mediums have the same index of refraction.
D. Cannot be determined.
Correct Answer: A. Medium 1 has a larger index of refraction.
Explanation: The larger the index of refraction, the more slowly a wave travels through the
medium, and the closer together the wave fronts will be. The wave fronts in medium 1 are
closer together, so medium 1 has a higher index of refraction. If the medium that the light
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Refraction Gizmo : ExploreLearning
originates in has a higher index of refraction than the medium the wave moves into, then
the angle of incidence will be smaller than the angle of refraction.
4. If index of refraction 1 is 1.5, index of refraction 2 is 2.0, and the angle of incidence is 45
degrees, what is the angle of refraction?
A. 16 degrees
B. 32 degrees
C. 48 degrees
D. 64 degrees
Correct Answer: B. 32 degrees
Explanation: Using Snell's law,
θ2 = sin
So, θ2
−1
(n1 sin θ1 /n2 )
= sin
−1
(1.5 ⋅ sin 45/2.0) = 32.0
degrees.
5. A jeweler is determining the optical properties of an unknown blue gemstone. She uses an
angle of incidence of 62°, and measures an angle of refraction of 30°. Assuming the index of
refraction of air is 1.0, what is the index of refraction of the gem?
A. 1.54
B. 1.77
C. 2.16
D. 2.42
Correct Answer: B. 1.77
Explanation: By Snell's law,
n1 sin(θ1 ) = n2 sin(θ2 )
So, 1 ⋅ sin(62∘ )
∘
= n2 ⋅ sin(30 )
, or n2
∘
∘
= sin(62 )/ sin(30 ) = 1.77
This is close to the index of refraction for sapphire. Many gemstones can be identified by
their index of refraction. Quartz has an index of refraction of 1.54, cubic zirconia 2.16, and
diamond 2.42. The high index of refraction of diamonds contributes to the brilliance and
"fire" that diamonds are famous for.
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