1. How does reflection change a
17.3 Key Concepts
How does reflection change a
wave?
What causes the refraction of a
wave when it enters a new medium?
What factors affect the amount of diffraction of a
What are two types of interference?
What wavelengths will produce a standing wave?

2. The ripples visible on the bottom of the pool are caused by light shining through ____________ waves.
surface

3. Ex: When waves bounce of the side of a pool ________
Reflection
Reflection occurs when a wave ____________ off a surface that it cannot pass through.
Ex: When waves bounce of the side of a pool
________
bounces
wall
Reflection does not change the speed or frequency of a wave, but the wave can be flipped ______________.
upside down

4. Refraction
Refraction is the _____________ of a wave as it enters a _____ _____________ at an ____________.
bending
new
medium
angle
When a wave enters a medium at an angle, refraction occurs because ____________ of the wave moves more ______________ than the other side.
one side
slowly

5. Refraction
Grass
Gravel
Ex: Think of a lawnmower when it is pushed at an angle from the grass onto the gravel.
The wheel on the _____________ slows down, but the other wheel is still moving at a faster speed on the grass.
Left wheel is still rolling faster on grass.
Direction changes.
gravel
Mower pivots because the right wheel moves more slowly when it reaches gravel.

6. An ocean wave bends or ____________ as it approaches the shoreline.
Refraction
An ocean wave bends or ____________ as it approaches the shoreline.
The __________ water can be considered a new medium
refracts
shallow

7. Refraction
The ________ side of the wave reaches the shallow water first and _______ down, causing the wave to bend
If a wave front approaches a shoreline perfectly ______________, no refraction occurs
left
slows
parallel

8. Diffraction
Diffraction is the bending of a wave as it moves _____________ an obstacle or passes through a ________________ opening.
around
narrow
A wave diffracts more if its wavelength is _______________ compared to the ________ of an opening or obstacle.
large
size

9. Diffraction also occurs when a wave encounters an __________________.
This wave diffracts, or _______________, after it passes through a narrow opening.
Diffraction also occurs when a wave encounters an __________________.
spreads out
obstacle

10. Interference
Interference occurs when two or more waves ________________ and combine together.
overlap
Two types of interference are _______________ interference and _______________ interference.
constructive
destructive

11. Interference
When waves collide, they can occupy the same region of space and then continue on.
Constructive interference occurs when two or more waves combine to produce a wave with a _____________ displacement.
Destructive interference occurs when two or more waves combine to produce a wave with a _________________ displacement.
larger
smaller

12. Constructive Interference
Two waves with equal frequencies travel in opposite directions.
When a _________ meets a ______________, the result is a wave with an increased amplitude.
crest
crest

13. Destructive Interference
Two waves with equal frequencies travel in opposite directions.
When a ___________ meets a ____________, the result is a wave with a reduced amplitude.
crest
trough

14. Standing Waves
A standing wave is a wave that appears to stay in ________________— it does not seem to move through the medium.
Ex: Think of plucking a guitar
string
one place
A standing wave forms only if _________ a wavelength or a _______________ of half a wavelength fits exactly into the _____________ of a vibrating cord.
half
multiple
length

15. incoming wave on a guitar string? And a reflected wave?
Standing Waves
Interference occurs as the _____________ waves pass through the ______________ waves.
What would cause an
incoming wave on a guitar
string?
And a reflected wave?
incoming
reflected
plucking a string
wave bouncing off ends

16. Standing Waves
A ___________ is a point on a standing wave that has no displacement from the rest position.
At the nodes, there is complete ______________ interference between the incoming and reflected waves.
An ______________ is a point where a crest or trough occurs midway between two nodes.
node
destructive
antinode

17. These photos show standing waves for two different frequencies.
________ wavelength equals the length of the cord.
________ wavelengths equal the length of the cord.
One
Two

18. Assessment Questions
The property of waves bending as they pass through a narrow opening is called
reflection.
refraction.
diffraction.
destructive interference.

19. When does refraction of a wave occur?
Assessment Questions
When does refraction of a wave occur?
The wave cannot enter the new medium.
The wave enters a new medium at an angle.
The wave enters a new medium at a parallel position.
Part of the wave enters a new medium and part is reflected.

20. Assessment Questions
A 6-meter rope is tied to a hook in the wall. Which of the following wavelengths can produce a standing wave?
1.5 m
2.5 m
3.5 m
4.5 m

21. Assessment Questions
4. The amount of diffraction of a wave increases as the size of the obstacle causing the diffraction decreases. True False