1. Integrated Science
Unit 4, Chapter 12

2. Unit Four: Sound and Waves
Chapter 12 Waves
12.1 Waves
12.2 Waves in Motion
12.3 Natural Frequency and Resonance

3. Chapter 12 Learning Goals
Learn the role waves play in our daily lives, including our effort to communicate.
Learn the parts and shapes of waves.
Model transverse and longitudinal waves and their characteristics with a stretched string.
Explore the properties of waves (like reflection and diffraction) with water.
Investigate resonance and harmony using an electronic synthesizer.
Learn how natural frequency and resonance are involved in making music.

4. Chapter 12 Vocabulary Terms
circular waves
continuous harmonics
constructive interference
crest hertz
destructive interference
diffraction
fundamental plane
longitudinal wave
natural frequency
reflection
refraction
resonance
response
transverse wave
trough
standing wave
wave fronts
waves

5. 12.1 Waves How do we make and describe waves? Key Question:
*Read text section 12.1
AFTER Investigation 12.1

6. 12.1 Waves
If we poke a ball floating on water, it will bob up and down (harmonic motion).
The oscillating ball creates a wave on the water surface.
The first ball can make a second ball that is farther away oscillate.
Explain the transfer of energy.

7. 12.1 Why study about waves?
useful
puzzling

8. 12.1 Evidence of waves Anytime you see a vibration that moves
Anything that makes or responds to sound
Anything that makes or responds to light
Anything that transmits information through the air (or space) without wires
cell phones, radio, and television.
Anything that allows you to “see through” objects
ultrasound, CAT scans, MRI scans, and X rays

9. 12.1 Transverse and Longitudinal Waves
A transverse wave has its oscillations perpendicular to the direction the wave moves.
A longitudinal wave has oscillations in the same direction as the wave moves.

14. 12.1 Frequency, Amplitude and Wavelength

15. 12.1 Wavelength

16. frequency (cycles/sec)
12.1 Speed
frequency (cycles/sec)
speed (m/sec)
v = f l
wavelength (m)

17. 12.2 Graphs of Harmonic Motion
Key Question:
How do waves move and interact with things?
*Read text section 12.2 AFTER Investigation 12.2

18. 12.2 Waves in Motion Waves have crests and troughs.
The crest of a wave is sometimes called a wave front.
The shape of a wave is determined by its wave front.

23. 12.3 Natural Frequency and Resonance
Key Question:
What is resonance and why is it important?
*Read text section 12.3
AFTER Investigation 12.3

24. 12.3 Natural Frequency and Resonance
All things in the universe have a natural frequency, and many things have more than one.
If you know an object’s natural frequency, you know how it will vibrate.
If you know how an object vibrates, you know what kinds of waves it will create.
If you want to make specific kinds of waves, you need to create objects with natural frequencies that match the waves you want.

25. 12.3 An example of resonance

26. 12.3 Standing Waves and Harmonics