Waves & Sound

What is a wave?

What is a wave?• Waves are…• Disturbances that

transfer energy from one place to another

• Waves do not transfer matter from one place to another, only energy

• Think about that in relation to the image on the left…

Properties of waves

• Amplitude (A)--maximum displacement from equilibrium (large amplitude sounds are LOUD)

• Wavelength (λ)--distance from crest to crest, trough to trough, or from start to end (also distance wave travels in one cycle)

Properties of waves (cont.)

• Frequency (f)--is the number of cycles or oscillations per unit time– Measured in cycles

per second called Hertz (Hz)

• Listen to sounds of different frequencies by using the Sound java applet located here.

Properties of Waves (cont.)• Period (T)—the time it

takes for one complete oscillation or cycle.

• Wave Speed (v)—rate at which a wave travels

• Sound travels at 343 m/s at STP

• Light travels at 300,000,000 m/s !

Types of Waves

• Longitudinal (compressional)– Medium oscillates

along the direction the wave travels

• Transverse– Medium oscillates

perpendicular to the direction the wave travels

Longitudinal WaveSuch as Sound

Longitudinal wave animation

Sound Wave Radiating in All Directions

Sound wave radiation

Figure 19.4

Figure 19.5

Transverse Wave

Transverse and water waves

Types of Waves (cont.) Examples

• Longitudinal• Transverse

Figure 19.8A

Figure 19.8B

Figure 19.10

Figure 19.11

Unnumbered Figure 2 Pg. 348

Figure 19.12

Figure 19.13

Figure 19.14

Figure 19.15

Figure 19.16

Figure 19.17

Figure 19.18

Figure 19.19

Figure 19.20

Figure 19.21

Figure 19.22

Figure 19.24