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Extensible Markup Language  |  1995-08-15  |  3KB  |  34 lines
  1. <?xml version="1.0" encoding="utf-8" ?>
  2. <!DOCTYPE card PUBLIC "-//Apple, Inc.//DTD card V 2.0//EN" "" >
  3. <card>
  4.     <id>22312</id>
  5.     <filler1>0</filler1>
  6.     <cantDelete> <false /> </cantDelete>
  7.     <showPict> <true /> </showPict>
  8.     <dontSearch> <false /> </dontSearch>
  9.     <owner>5472</owner>
  10.     <link rel="stylesheet" type="text/css" href="stylesheet_3106.css" />
  11.     <content>
  12.         <layer>background</layer>
  13.         <id>25</id>
  14.         <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>
  15.     </content>
  16.     <content>
  17.         <layer>background</layer>
  18.         <id>26</id>
  19.         <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>
  20.     </content>
  21.     <content>
  22.         <layer>background</layer>
  23.         <id>23</id>
  24.         <text>ΓÇó QUANTUM THEORY AND RELATIVITYΓÇó ACOUSTICSΓÇó OPTICSΓÇó ELECTROMAGNETISMΓÇó COASTSΓÇó THE OCEANSΓÇó MEDICAL TECHNOLOGYΓÇó RADIO, TELEVISION AND VIDEOΓÇó SEEING THE INVISIBLE</text>
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  26.     <content>
  27.         <layer>background</layer>
  28.         <id>36</id>
  29.         <text>2630323496100242326332</text>
  30.     </content>
  31.     <name>p028-8</name>
  32.     <script></script>
  33. </card>
  34.