1. Wave Motion and Sound

2. Part 1: Wave Motion

3. Which of the following is an example of a mechanical wave?
Sound
Light
Microwaves
X-rays
Response Grid

4. P4.4A
Describe specific mechanical waves (eg on a demonstration spring, on the ocean) in terms of wavelength, frequency, speed and amplitude.

5. Wave Motion A pulse is a single disturbance.
A wave is a series of pulses traveling through space.
Pulse
Wave: Picture shaking a slinky up and down

6. Wave Motion
Mechanical waves: need a medium (substance) through which to travel
Examples: water waves, slinky waves, sound waves
Electromagnetic waves: do not need a medium through which to travel
Examples: radio waves, microwaves, light, UV rays, x-rays

7. Which of the following is an example of a electromagnetic wave?
Sound
Water
X-Rays
Response Grid

8. Which of the following is an example of a mechanical wave?
Sound
Light
Microwaves
X-rays
Response Grid

9. Particle Motion All waves can travel two different ways:
Transverse Wave: particles vibrate perpendicular to direction of traveling wave
Longitudinal Wave: particles vibrate parallel to direction of traveling wave

10. Video
Play Transverse vs. Longitudinal Video

11. Which type of wave does not need to travel through a medium?
Electromagnetic
Mechanical
Response Grid

12. Transverse Wave Crest: top point of wave (green dots)
Trough: bottom point of wave (orange dots)
Amplitude: distance from crest to x-axis
Wavelength: length of one complete “cycle”
crest
trough

13. Transverse Wave Frequency: number of “cycles” that pass per second
Can be number of crests, troughs, or wavelengths that pass per second
Symbol: f
Units: 1/seconds or Hertz
crest
trough

14. Transverse Wave Applet
Wave on a string Applet
Use the applet to change Amplitude and Frequency
Set to oscillate, no end, zero damping

15. Which of the following is the wavelength of the wave pictured below?
Response Grid A C B D

16. Which of the following is the amplitude of the wave pictured below?
Response Grid A C B D

17. Which of the following is the trough of the wave pictured below?
Response Grid A C B D

18. Which of the following is the crest of the wave pictured below?
Response Grid A C B D

19. P4.4C
Compare and contrast transverse and compression (longitudinal) waves in terms of wavelength, amplitude and frequency.

20. Transverse Wave (Review)
Crest: top point of wave (green dots)
Trough: bottom point of wave (orange dots)
Amplitude: distance from crest to x-axis
Wavelength: length of one complete “cycle”
crest
trough

21. Compressional Waves Compression: compressed area of wave
Rarefaction: spread out area of wave
Wavelength: length of one complete “cycle” of wave
measured from compression to compression
Frequency: number of cycles that pass per second
Rarefaction

22. Longitudinal vs. Transverse

23. Which of the waves below has the larger wavelength?
Wave A
Wave B
Wave B
Response Grid
Wave A

24. Which of the waves below has the larger amplitude?
Wave A
Wave B
Wave B
Response Grid
Wave A

25. Compression is to crest as rarefaction is to
Amplitude
Frequency
Wavelength
Trough
speed
Response Grid

26. The number of wave crests per second is called
Wavelength
Frequency
Speed
amplitude
Response Grid

27. P4.4B
Identify everyday examples of transverse and compression (longitudinal waves)

28. Example: Longitudinal Wave
Sound is a longitudinal wave!!
When you speak, you vocal cords vibrate and “bump” the air particles close by. These particles then bump the next particle, etc.
If there were no air particles, there could be no propagation of sound!!
Is there sound in outer space??

29. EM Waves

30. Which of the following is NOT a transverse wave?
Light
Water
Rope
sound
Response Grid