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Sound: Nodal Points

  1. Aug 12, 2006 #1
    Hello everybody, my apologies if this is a stupid question.

    Under the sound (specifically vibrations and waves) unit in my textbook, it briefly mentions nodes. However, it merely describes it as a "centre point [that] always stays at the equilibrium and never vibrates."

    My question is: what is the significance of mentioning these nodal points? (Please don't take this the wrong way, I'm all for extra tidbits of info, but I'm curious as to why the textbook bothers to mention this phenomena.)

    Thanks for all your help!
  2. jcsd
  3. Aug 12, 2006 #2


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    If you are thinking of a string vibrating, the nodal points are the points where there is no deflection in the string. There will be a different number of nodes depending on what mode (with an M) the string is vibrating. The applications of nodes spreads to many aspects in vibration. So, in a string, would it do you much good to have to put your finger on a fret board in an attemot to get a specific tone from the string, only to find the spot where your finger goes is on a node?
  4. Aug 16, 2006 #3


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    A vibrating string can support several standing waves - the fundamental, first harmonic, second harmonic (overtones). The amount of nodes will increase as these wave forms are generated. Nodes also appear at the endpoints of the string. In spite of this it can still vibrate!
  5. Aug 17, 2006 #4


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    Gold Member

    The nodal points are also an easy way to measure the frequency (if you dont have a stroboscope) , you just count the number of nodes, measure the length of the string and it's tension and you have all the information needed to calculate frequency.
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