1. Waves and Wave Properties
Presentation for lesson 2: Waves and Wave Properties, in the Waves: The Three Color Mystery unit
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Waves and Wave Properties

2. Why are we able to see?
Answer: Because there is light.
And…what is light?
Answer: Light is a wave.

3. So…what is a wave?
Answer: A wave is a disturbance, or vibration, that carries energy from place to place.
A wave does NOT carry matter with it! It just moves the matter as it goes through it.
Think of a stadium wave: the people are moving up and down, but the wave goes around the stadium

4. For the most part waves MUST have a medium in order to move.
Example of Waves: Sound, light, radio waves, earthquakes and many more.
These are called mechanical waves.

5. Three Types of Waves
Transverse
Longitudinal
Surface

6. Wave Types
Transverse waves: Waves in which the particles move perpendicular to the direction of the wave.
Sound Waves and Light Waves behave like Transverse Waves

7. 2. Longitudinal waves: Waves in which the medium moves back and forth in the same direction as the wave.
A spring (slinky) or a tuning fork behaves like a compressional or longitudinal wave.

8. 3. Surface waves: a wave where particles on the surface of a medium move in a circular motion. A combination of transverse and longitudinal waves.
Example: an ocean wave at the surface.

9. Parts of the Wave
1. Medium: Material that the wave travels through (air, water, carbon, ice, etc…) 2. Crest: the highest point of the wave 3. Trough: the lowest point of the wave

10. 4. Amplitude (A) : Max displacement from rest.

11. Remember that for compressional waves, the points where the medium is close together are called compressions and the areas where the medium is spread apart are called rarefactions.
The closer together and further apart the particles are, the larger the amplitude.
compression
rarefaction

12. 5. Wavelength: The distance travelled by a single wave
5. Wavelength: The distance travelled by a single wave. (From one point to the exact same point along the wave)

13. Putting it all together
Wavelength

14. 1 Hz is equivalent to 1 cycle/second.
Frequency (f): How many waves go past a point in one second; unit of measurement is hertz (Hz).
1 Hz is equivalent to 1 cycle/second.
The higher the frequency, the more energy in the wave.
10 waves going past in 1 second = 10 Hz
1,000 waves go past in 1 second = 1,000 Hz
1 million waves going past = 1 million Hz

15. Period (T): Time it takes (in seconds) for a wave to make one complete cycle or one wavelength.

17. Example #1

18. Wave Speed
Answer: speed = 2 m x 500 Hz = 1000 m/s

19. Example # 2

20. Example #2
The distance between successive crests in a series of water waves is 4.0 m, and the crests travel 8.6 m in 5.0s. Calculate the frequency of a block of wood bobbing up and down on these water waves.
4.0 m
d = 8.6 m
t = 5.0s