Chapter 32 – Refraction
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Reading Assignment
All sections (1 – 10)
End of Chapter Problems (Online Homework)
Prior Knowledge
-What light is (from a physics point of view)
-The speed of light is a constant 3×108
-How wavelength relates to color
Vocabulary
-Refraction
-Medium
-Interface
-Index of Refraction
-Total Internal Reflection
-Critical Angle
-Dispersion
Equations
n=
Speed of Light in a Vacuum (3 × 108 m/s)
Speed of Light in a Medium
ni sin θi = nr sin θ r
sin θ c =
n2
n1
OR
n=
c
v
Section 0: Introduction
32.0.1
When does light refract? (What does it have to be doing to refract?)
32.1.1
Can you explain the following image…
(Hint: Refraction…)
Section 1: Refraction
32.1.1
Why does light refract when it changes the medium that it is traveling through?
32.1.2
Is it only light waves that refract? Give an example of another type of wave that might refract.
Section 2: Index of Refraction
32.2.1
Define the Index of Refraction:
32.2.2
Which has a higher index of refraction
Water / Vegetable Oil
(Circle One)
32.2.3
If light travels through a certain medium with a speed of 2.45×108 m/s then what is the index of
refraction of that medium?
32.2.4
Your book says that index of refraction depends on wavelength, what does this mean? (For
example if red light and green light enter a medium what will happen to each one?)
32.2.5
There is a physics law that says nothing…NOTHING…can travel faster than the speed of light
in a vacuum. So do you think that the index of refraction can ever be less than one? Why or
why not?
Section 3: Snell’s Law
32.3.1
Snell’s Law tells you how far light will bend when passing from one medium into another.
Write down the mathematical form of Snell’s Law.
32.3.2
If light passes into a medium with n = 1.3 and an angle of incidence of 42o to a medium with n =
1.5, what will be the angle of refraction?
32.3.3
If the incident medium has a higher index of refraction than the refraction medium will the light
bend toward or away the normal line?
32.3.4
If light passes from air, into glass, then back into air, what will happen to the angle of incidence
(entering the glass) to the angle of refraction (leaving the glass).
Section 4: Interactive Checkpoint Snell’s Law
Work through this interactive example and write the final answer below for the index of
refraction of the second medium.
Section 5: Everyday Effects of Refraction
This section is interesting so read it and then try and come up with one more example of
refraction in everyday life that the book doesn’t mention.
Section 6: Why Refraction Occurs
32.6.1
After reading the mechanical analogy of why refraction occurs when moving between a medium
where you travel at two different speeds answer the following question. Does refraction occur if
the angle of incidence is zero degrees? Use the car on ice analogy and figure out what would
happen if it entered the ice straight on, does it change direction? Then see if you can use Snell’s
Law and prove your answer.
Section 7: Interactive Problem – Helicopter and Submarines
Play the game until you win and then list the angles that you used to defeat the computer.
Section 8: Total Internal Reflection
32.8.1
When light reaches a certain angle called the _____________ angle it has an angle of reflection
greater than or equal to __________ degrees. This is called __________ __________
__________.
32.8.2
Determine the critical angle for light going from vegetable oil (index of refraction equal to 1.42)
to water (index of refraction equal to 1.33).
32.8.3
Can you ever have total internal reflection when moving from a medium with a low index of
refraction to a medium with a high index of refraction? Why or why not?
Section 9: Dispersion and Prisms
32.9.1
List the colors of the rainbow in order (think ROY G. BIV).
32.9.2
Describe below how rainbows are formed.
32.9.3
Now that you know what rainbows actually are (from a physics standpoint) is it possible to ever
get to that pot of gold that resides at the end of one?
32.9.4
Think hard…how would double rainbows be formed? (These are real things…have you ever
seen one?)
Section 10: Gotchas
Try to create three multiple choice questions (remember, if they’re really good you could see
them on a test!)
Section 11: Summary
Add some of your own notes to the summary. (Don’t just copy the summary word for word!)