1. 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. 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 trough Rest position

3. 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 Rest position wavelength

4. 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.

5. 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.

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

9. 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.

10. 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. 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.

12. Measuring Amplitude in a Transverse Wave amplitude crest trough