1. Waves

2. Waves
A wave is a rhythmic disturbance that carries energy through matter or space.
Examples of Waves:
Light
Radio waves
Sound
Electric signals
Ocean waves
Earthquakes
Vibrations in structures (musical instruments)

3. Waves All waves have a source and travel through a medium
The source is the thing that is causing the wave
The medium is what the wave travels through

4. Waves Mechanical waves
Mechanical waves require a medium made of matter.
Air (sound waves)
Water (sound waves, sonar)
Rock (earthquake)
Interface between water and air (ocean waves)
There are three types of mechanical waves:
longitudinal
transverse
surface

5. Waves Longitudinal waves
A longitudinal wave is a wave that vibrates parallel to the direction of the wave motion
Example: sound waves

7. Waves Transverse waves
A transverse wave is a wave that vibrates perpendicular to the direction of wave motion.
Example: waves on a rope or string

9. Waves
Surface waves
Surface waves exist at the interface of two media (e.g., water and air  ocean waves)
They exhibit characteristics of both longitudinal and transverse waves.
Examples: ocean waves, surface-traveling earthquake waves

11. Pulse vs. periodic waves
Speed and amplitude apply to both types
Period, frequency, wavelength apply only to periodic waves

12. Waves
Anatomy of a periodic wave:

13. Waves Speed Amplitude Depends only on the medium
Measured by tracking a pulse
(v = x/t)
Amplitude
Is how “big” the wave is
Depends on how the wave is generated
Is proportional to the wave’s energy

14. Waves Wavelength Period Shortest distance between crests (or troughs)
Represented by the Greek letter lambda, 
Period
Like the period of a simple harmonic oscillator
The time it takes the wave to repeat itself (one complete cycle)
Represented by the letter T

15. Waves
Frequency
Is the number of complete oscillations a wave makes each second
Represented by the letter f
Frequency and period are related by the equation:
f = 1/T
Frequency and period depend only on the source of the wave

16. Waves
The wavelength, , depends on both period (or frequency) and speed
Therefore, wavelength depends on both the source and the medium
 = vT = v/f
Wave speed equation:
v = f

17. Example Calculation
The crest of a periodic ocean wave passes the same point once every 17 s. Find the speed of the wave if the wavelength is 130m.
T = 17 s
 = 130 m
v = f = /T = (130 m)/(17 s) = 7.6 m/s