Waves & Sound

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… 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) 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. here 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. 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 ! 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 (compressional) –Medium oscillates along the direction the wave travels Transverse –Medium oscillates perpendicular to the direction the wave travels

Longitudinal Wave Such 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

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Figure 19.24