1. An Introduction to Waves
3U Physics

2. What is a wave?
A wave is a disturbance which carries energy from one location to another.

3. What is a wave?
A wave is a disturbance which carries energy from one location to another.
The material the disturbance travels through is the ?
The movement of the disturbance is referred to as ?

4. What is a wave?
A wave is a disturbance which carries energy from one location to another.
The material the disturbance travels through is the medium.
The movement of the disturbance is referred to as ?

5. What is a wave?
A wave is a disturbance which carries energy from one location to another.
The material the disturbance travels through is the medium.
The movement of the disturbance is referred to as propagation.

6. 2 Types of Waves
A longitudinal wave is a wave in which the particles of the medium move in a direction parallel to the direction of propagation.

7. 2 Types of Waves
A longitudinal wave is a wave in which the particles of the medium move in a direction parallel to the direction of propagation.

8. 2 Types of Waves
A longitudinal wave is also called a pressure wave or a sound wave.

9. 2 Types of Waves
A longitudinal wave is also called a pressure wave or a sound wave.
The regions of increased pressure/density are called ?.
The regions of decreased pressure/density are called ?.

10. 2 Types of Waves
A longitudinal wave is also called a pressure wave or a sound wave.
The regions of increased pressure/density are called compressions.
The regions of decreased pressure/density are called ?.

11. 2 Types of Waves
A longitudinal wave is also called a pressure wave or a sound wave.
The regions of increased pressure/density are called compressions.
The regions of decreased pressure/density are called rarefactions.

12. 2 Types of Waves
A transverse wave is a wave in which the particles of the medium move in a direction perpendicular to the direction of propagation.
Although sound waves are not transverse waves, we often represent them as transverse waves because transverse waves are easier to draw.

13. 2 Types of Waves
The vertical axis represents not displacement but pressure.

14. Snapshot of a Transverse Wave
The dashed line represents the equilibrium position of the particles.

15. Snapshot of a Transverse Wave
The positions of maximum displacement are referred to as crests (positive displacement) and troughs (negative).
The maximum displacement is the amplitude.

16. Snapshot of a Transverse Wave
The positions of maximum displacement are referred to as crests (positive displacement) and troughs (negative).
The maximum displacement is the amplitude.
Amplitude = Energy

17. Snapshot of a Transverse Wave
The distance between one crest and the next crest (or one trough and the next trough) is the

18. Snapshot of a Transverse Wave
The distance between one crest and the next crest (or one trough and the next trough) is the wavelength, represented by

19. Snapshot of a Transverse Wave
The distance between one crest and the next crest (or one trough and the next trough) is the wavelength, represented by l.

20. Snapshot of a Transverse Wave
The time it takes one complete wavelength to pass a single point is the

21. Snapshot of a Transverse Wave
The time it takes one complete wavelength to pass a single point is the period, represented by

22. Snapshot of a Transverse Wave
The time it takes one complete wavelength to pass a single point is the period, represented by T.

23. Snapshot of a Transverse Wave
The time it takes one complete wavelength to pass a single point is the period, represented by T.

24. Snapshot of a Transverse Wave
The number of complete wavelengths that pass a single point in one second is the frequency, represented by f.

25. Frequency Frequency is measured in units of 1/s or s-1 or Hertz (Hz).
“I do not think that the wireless waves I have discovered will have any practical application.”

26. Wave Speed
The speed of a wave is therefore:

27. Wave Speed
The speed of a wave is therefore:

28. Wave Speed
The speed of a wave is therefore:

29. Wave Speed The speed of a wave is therefore:
The speed of a sound wave in air at room temperature (20oC) is 344 m/s.

30. Sound Wave Example
Calculate the wavelength of the sound wave produced by a 125 Hz tuning fork in air at 20oC.

31. Sound Trivia
A Victorian parlor trick was to listen to the pitch of a fly’s buzz, reproduce the musical note on the piano, and announce how many times the fly’s wings had flapped in one second. If the fly’s wings flap, say, 200 times in one second, then the frequency of their motion is f = 200/1 s = 200 s-1. The period is one 200th of a second, T = 1/f = (1/200) s = s.

32. Sound Wave Example
Calculate the wavelength of the sound wave produced by a 125 Hz tuning fork in air at 20oC.

33. Sound Wave Example
Calculate the wavelength of the sound wave produced by a 125 Hz tuning fork in air at 20oC.

34. More Practice Inquiry Activity: Slinky Waves
Homework: An Introduction to Waves