<text><span class="style10">ave Theory (3 of 11)</span><span class="style7">Wave motions transfer energy - for example, sound waves, seismic waves and water waves transfer mechanical energy. However, energy is lost as the wave passes through a medium. The amplitude diminishes and the wave is said to be at tenuated. There are two distinct processes - </span><span class="style26">spreading</span><span class="style7"> and </span><span class="style26">absorption</span><span class="style7">. In many cases there is little or no absorption - electromagnetic radiation from the Sun travels through space without any absorption at all, but planets that are more distant than the Earth receive less radiation because it is spreading over a larger area and so the </span><span class="style26">intensity<</span><span class="style7"> (the ratio of power to area) decreases according to an inverse-square law. The same applies to sound in the atmosphere. In some cases, however, energy is absorbed in a medium, as, for example, when light enters and exposes a photographic film, or when X-rays enter flesh. For homogeneous radiation, absorption is </span><span class="style26">exponential</span><span class="style7">, for example if half the radiation goes through 1 mm of absorber, a quarter would go through 2 mm and an eighth through 3 mm.</span><span class="style10"></span></text>
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<text><span class="style10">. Amplitude</span><span class="style7"> is the maximum displacement from the equilibrium position.</span><span class="style10">4. Wave attenuation.</span><span class="style7"> Energy is lost as a wave travels through a medium-- the amplitude is reduced, and the wave is said to be attenuated.</span></text>
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<text>ΓÇó QUANTUM THEORY AND RELATIVITYΓÇó ACOUSTICSΓÇó OPTICSΓÇó ELECTROMAGNETISMΓÇó COASTSΓÇó THE OCEANSΓÇó MEDICAL TECHNOLOGYΓÇó RADIO, TELEVISION AND VIDEOΓÇó SEEING THE INVISIBLE</text>
