Waves
Unit C-Chapter 1.3
Waves Behave in Predictable Ways
Answer Key
Name:
Date:
Core:
Directions: Read pages C24-C28 and answer the following questions.
1. What behaviors do all waves have in common?
Answer:
Reflection, Refraction, Diffraction
2. What is reflection?
Answer:
The bouncing back of a wave after it strikes a
barrier is called reflection.
3. What is an example of reflection?
Answer:
The water waves at the end of the swimming pool.
The waves cannot travel through the wall of the
pool. Instead, the waves bounce off the pool wall.
4. Draw the illustration of reflection on page C25.
Answer:
Illustration of Reflection on Page C25.
5. What is an example of “sound waves” reflecting?
Answer:
Sound Waves reflecting off the walls of a canyon
produce an echo.
6. What is an example of “light waves” reflecting?
Answer:
Light waves reflect off a smooth metal behind glass
letting you see an image of yourself in the mirror.
7. What is refraction?
Answer:
Refraction is the bending of a wave as it enters a
new medium at an angle other than 90 degrees.
8. What is an example of refraction?
Answer:
The light waves refract as they pass from air to
water, making the straw look split.
9. What happens when sound waves strike solid rock?
Answer:
They reflect from the rock as in an echo.
10. Why do you see distorted shapes when you look into the water in a swimming pool?
Answer:
Light waves bend, or undergo refraction, when they
pass from the air into the water. The refraction
distorts underwater object
11. What is diffraction?
Answer:
Diffraction is the spreading out of waves through
an opening or around the edge of an obstacle.
12. Does diffraction occur with all types of waves?
Answer:
Yes!
13. Look at the photograph of page C26 and answer the following questions.
A. Through what medium are the waves moving?
Answer:
Water
B. From what perspective are you viewing the waves?
Answer:
From Above
C. What happens to the waves as they go through the opening?
Answer:
The waves spread out.
14. What is an example of how “sound waves” diffract?
Answer:
Turn on a TV or stereo and walk into another room.
Listen to the sound with the door closed and then
open. Then try moving around the room. You can
hear the sound wherever you stand because the
waves spread out, or diffract, through the doorway
and reflect from the walls.
15. Illustrate (draw) the photograph on page C27. This photograph shows water waves diffracting
as they pass large rocks in the water.
Answer:
Illustration on Page C27.
16. Describe what happens when waves diffract.
Answer:
Waves spread out as they diffract around edges of
opening and obstacles.
17. What is interference?
Answer:
The meeting and combining of waves.
18. What is constructive interference?
Answer:
The adding of two waves is called constructive
interference.
19. Draw the diagram of constructive interference on page C27.
Answer:
Diagram on Page C27
20. What is destructive interference?
Answer:
Imagine two very similar waves come together. This
time, however, the crest of one wave joins briefly
with the trough of the other. The energy of one
wave is subtracted from the energy of the other.
The new wave is therefore smaller than the original
wave. This can cause the two waves to cancel each
other out. This is destructive interference.
21. Draw the diagram of destructive interference on page C28.
Answer:
Diagram on Page C28
22. Summarize in your own words what happens during interference.
Answer:
Interference is the meeting and combining of
waves.
Chapter Review 1.3
Directions: Complete questions 1-5 on page C28. Only write your answers.
1. Explain what happens when waves encounter a medium that they cannot travel through?
Answer:
Waves reflect.
2. Describe a situation in which waves would diffract.
Answer:
Ocean waves hit a spot of land.
3. Describe two ways that waves are affected by interference.
Answer:
Amplitudes can add up or cancel each other out.
4. Explain how reflection and diffraction can happen at the same time in a wave.
Answer:
When a wave hits a partial barrier, the part of the
wave that hits the barrier reflects into the
oncoming waves. The part of the wave that passes
through the gap in the barrier diffracts.
5. How is interference similar to net force? How do you think the two concepts might be related?
Hint: Think about how forces are involved in wave motion.
Answer:
Forces are responsible for moving a wave medium
up and down as a wave passes through it. Forces
can be added or subtracted on a wave medium just
as they can on any object.
6. Imagine that you make gelatin it a long shallow pan. Then you scoop the gelatin out of one
end of the jar and add icy cold water to the exact same depth as the gelatin. Now suppose you
set off waves at the water end. What do you think will happen when the waves, meet the
gelatin?
Answer:
Answers could describe refraction, as waves meet and
enter a new medium, or reflection, as waves encounter
a barrier.