1. Wave Properties Learning Goals:
Define wavelength, frequency, period, and amplitude.
Describe the relationship between frequency and wavelength.
Explain how a wave’s energy and amplitude are related.
Calculate wave speed.

2. Parts of a Wave Crest: high point of the wave form
Trough: low point of the wave form
Compression: more dense region of a longitudinal wave
Rarefaction: less dense region of a longitudinal wave
crest
**Crest: high point of the wave form
**Trough: low point of the wave form
**Compression: more dense region of a longitudinal wave
**Rarefaction: less dense region of a longitudinal wave
Rest position
trough

3. Wave Properties Wavelength:
Defined - distance between one point on a wave and the nearest point just like it Distance from…
1) Crest to crest 2) Trough to trough 3) Start of one compression to the next 4) Start of one rarefaction to the next
wavelength
**distance between one point on a wave and the nearest point just like it
distance from crest to crest OR
trough to trough OR
start of one compression to the start of the next compression OR
start of one rarefaction to the start of the next rarefaction
wavelength
wavelength
wavelength
Rest position

4. Wave Properties Frequency:
Defined - the number of wavelengths (or number of vibrations) that pass a fixed point each second
Frequency is expressed in hertz (Hz).
A frequency of 1 Hz means that one wavelength (or one vibration) passes by in one second. Two vibrations per second is 2 Hz.
In SI units, 1 Hz is the same as 1/s.
**The number of wavelengths (or number of vibrations) that pass a fixed point each second

5. Wave Properties Period:
Defined - the amount of time it takes one wavelength to pass a point, measured in seconds
As the frequency of a wave increases, the period decreases.
**the amount of time it takes one wavelength to pass a point; measured in seconds.

6. Wave Properties Period (continued): Consider the following:
A wave has a frequency of 2 Hz. This means that two wavelengths pass a point in one second. How much time does it take for one wavelength to pass a point?
Answer: 1/2 or 0.5 second, so the period of this wave is 0.5 s.

7. Wave Properties Period (continued):
What about a wave with a frequency of 3 Hz. This means that three wavelengths pass a point in one second. How much time does it take for one wavelength to pass a point?
Answer: 1/3 or 0.33 second, so the period of this wave is 0.33 s.

8. Wave Properties Wavelength and Frequency:
The relationship is inversely proportional: when one increases, the other decreases.

9. Wave Properties Wave Speed:
Depends on… the medium it is traveling through. Sound waves usually travel faster in liquids and solids than they do in gases. However, light waves travel more slowly in liquids and solids than they do in gases or in empty space. Also, sound waves usually travel faster in material when the temperature of the material is increased.
**Depends on the medium it is traveling through. Sound waves usually travel faster in liquids and solids than they do in gases. However, light waves travel more slowly in liquids and solids than they do in gases or in empty space. Also, sound waves usually travel faster in material when the temperature of the material is increased.

10. Wave Properties v = ƒ λ Wave Speed (continued):
Calculated by multiplying its frequency times its wavelength
speed (in m/s) = frequency (in Hz) x wavelength (in m)
v = ƒ λ

11. Wave Properties Amplitude and Energy:
Amplitude is related to the energy transferred by a wave.
The greater the wave’s amplitude, the more energy the wave transfers.
**Amplitude is related to the energy transferred by a wave. The greater the wave’s amplitude, the more energy the wave transfers.

12. Wave Properties λ λ Measuring Amplitude in a Transverse Wave crest
**Draw a picture, and label it in your notes. λ
trough
Measuring Amplitude in a Transverse Wave