1. Types of Waves
Harmonic Waves
Sound and Light Waves
Superposition and Interference
The Doppler Effect
Resonance

2. Waves can be transverse
For example: Light waves, water waves and waves on a string...
Waves can be longitudinal
For example: Some seismic waves and sound waves…
Please, be patient. It takes awhile for the animations to start.

3. Waves in Time
Waves are like many springs oscillating in time.
They have a period (T),
a frequency (f) and
an amplitude (A). T t
f = 1/T

4. Waves in Space
Waves also oscillate in space.
They have a wavelength and
a speed.

5. Sound is a longitudinal wave
It travels through any gas, solid or liquid as a variation in pressure.
It has a speed that depends on the material (medium) that it travels through.
It has a wavelength and a frequency that determine the pitch.
It has an amplitude that determines the volume.

6. Light is a transverse wave
It travels through vacuum as a variation in electric and magnetic fields.
It has a speed that never changes.
c = 3 x 108 meters/second
It has a wavelength and a frequency that determine the color.
It has an amplitude that determines the intensity.

7. This is necessary to get the proper timing!
Transverse waves oscillate perpendicular to the direction of propagation.
Properties:
wavelength
amplitude
speed
propagation direction
polarization
This is necessary to get the proper timing!

8. Each point on a transverse wave oscillates perpendicular to the direction of propagation.
Properties:
period
frequency
amplitude
polarization t T
f = 1/T

9. Longitudinal waves oscillate parallel to the direction of propagation.
Properties:
wavelength
speed
propagation direction λ y x v

10. Each point on a longitudinal wave oscillates parallel to the direction of propagation.
Properties:
period
frequency
amplitude t T
f = 1/T x A

11. y x v λ Sound is a longitudinal wave
It travels through any gas, solid or liquid as a variation in pressure.
It has a speed that depends on the material (medium) that it travels through.
Properties:
wavelength
speed
propagation direction
period
frequency
amplitude
Pitch
Density (of medium)
Location
Volume λ y x v

12. y x Definition of interference
Constructive interference occurs when both waves have the same phase.
Destructive interference occurs when both waves have opposite phase. x y
phase

13. The frequency of sound changes depending on whether you move toward or away from the object emitting the sound
v is the velocity of the observer with respect to the source.
vs is the velocity of the sound.
v is positive if the observer is moving toward the source and negative if the observer is moving away from the source.

14. Other waves can only be made by force.
For pipes the wavelength of a wave must fit within the length of the pipe.
Other waves can only be made by force.
Note
Frequency
Middle C
261.7 D
293.7 E
329.7 F
349.2 G
392 A
440 B
493.9 C
523.3
Speed of sound in air is
343 meters/second = f x λ