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11-9 Energy Transported by Waves. Energy transported by waves is proportional to the square of the amplitude. Intensity (I) of a wave is defined as the power (or energy per unit of time) transported across unit area perpendicular to the direction of energy flow.
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11-9 Energy Transported by Waves Energy transported by waves is proportional to the square of the amplitude. Intensity (I) of a wave is defined as the power (or energy per unit of time) transported across unit area perpendicular to the direction of energy flow. I= power/area= (energy/time)/ area I= P/4pr2 I is proportional to 1/r2 I2 /I1 = r12 / r22 See Example 11-12 p330
11-10 Intensity Related to Amplitude and Frequency • E= ½ kA2 • E= 2p2mf2 A2 • Since m=rV and V=Sl….. • E= 2p2rSltf2 A2 • P=E/t =2p2rSlf2 A2 • Intensity (I) of a wave is the power transported across unit area perpendicular to the direction of flow… • I=P/S=2p2rvf2A2