<text><span class="style10">ave Theory (8 of 11)Interference</span><span class="style7">If several waves are traveling through a medium, the resultant at any point and time is the vector sum of the amplitudes of the individual waves. This is known as the </span><span class="style26">superposition principle</span><span class="style7">. Two or more waves combining together in this way exhibit the phenomenon of </span><span class="style26">interference</span><span class="style7">. If the resultant wave amplitude is greater than those of the individual waves then </span><span class="style26">constructive interference</span><span class="style7"> is taking place; if it is less, </span><span class="style26">destructive interference</span><span class="style7"> occurs. If two sound waves of slightly different frequencies and equal amplitudes are played together (for example two tuning forks), then the resulting sound has what is called </span><span class="style26">varying amplitude</span><span class="style7">. These varying amplitudes are called </span><span class="style26">beats</span><span class="style7"> and their frequency is the </span><span class="style26">beat frequency</span><span class="style7">. This frequency is equal to the difference between the frequencies of the two original notes. Listening for beats is an aid to tuning musical instruments: the closer the beats, the more nearly in tune is the instrument.</span></text>
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<text><span class="style10">1. Constructive interference</span><span class="style7"> results in the effect of the waves being combined.</span><span class="style10">12. Destructive interference</span><span class="style7"> results in the waves cancelling eacht other out.</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>