1. 6.1 Wave Properties

2. SAS Curriculum Pathways
Wave Properties

3. What happens if you drop a pebble into the water?
Wave Motion
What happens if you drop a pebble into the water?
The disturbance created by the pebble generates water waves that travel away from the disturbance

4. Wave is the Motion of a Disturbance
This disturbance causes water on the surface near that point to move, which in turn causes points farther away to move.
In this way, the waves travel outward in a circular pattern away from the original disturbance.

5. Wave is the Motion of a Disturbance
The water is the MEDIUM through which the disturbance travels.
The medium does not actually travel with the waves.
After the waves have passed, the water returns to its original position.

6. MECHANICAL WAVES = need MEDIUM
Most of the waves (sound waves, spring waves…) need MEDIUM (air, water…)

7. MECHANICAL WAVES = need MEDIUM
We call them MECHANICAL WAVES

8. ELECTROMAGNETIC WAVES = DO NOT need MEDIUM
They can travel through vacuum

9. PULSE PERIODIC WAVE Wave Types Non – repeating wave
Only single disturbance
PERIODIC WAVE
Repeating wave
Period = recurring at regular intervals

10. Describing Waves

11. The highest point on the waves
CREST
The highest point on the waves

12. The lowest point on the waves
Trough
The lowest point on the waves

13. The distance between successive crests or troughs
Wavelength
The distance between successive crests or troughs

14. Amplitude
The height of the wave

15. Frequency (f) measured in Hz
How often the waves and their source vibrate per second (how many wavelengths per second)

16. Period (T) measured in seconds
The time interval between vibrations (of the wavelength)
Inverse of FREQUENCY

17. 1.25 Hz
0.800 s
256 Hz
3.91 x 10-3s
0.25 Hz

18. Transverse Waves
A wave whose particles vibrate perpendicularly to the direction of the wave’s motion.
The spring is pulled sideways (up) while the pulse travels in the perpendicular direction (to the right)

19. Longitudinal Waves
When several turns of the spring are compressed and let go
The disturbance is in the same direction as the pulse will travel

20. Longitudinal Wave
A wave whose particles vibrate parallel to the direction the wave is traveling

21. Wave REFLECTION
When a wave encounters a boundary (shoreline, different medium…) and it is reflected back

22. The wave’s speed is changed AND it is BENT
Wave REFRACTION
When a wave hits a boundary at an angle OR the wave enters a new medium
The wave’s speed is changed AND it is BENT

23. The Wave Equation
Speed is equal to displacement divided by the time it takes to undergo that displacement
For waves, a displacement of one wavelength (λ) occurs in a time interval equal to one period of the vibration (T).

24. The Wave Equation Because frequency and period are inversely related,
Substituting this frequency relationship into the previous equation for
speed gives a new equation for the speed of a wave.

25. Example 1: A piano string tuned to middle C vibrates with a frequency of 262 Hz. Assuming the speed of sound in air is 343 m/s, find the wavelength of the sound waves produced by the string.

26. 200 Hz 1.5 m Practice Problems 6.1.1 If f doubles, λ is halved
If f halves, λ is doubled
200 Hz
1.5 m

27. Answer the Concluding Questions

28. 6.1 Review Questions (all)