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Electricity in crystals

  1. Aug 3, 2007 #1
    I wanted to ask if a continuous pressure on a piezoelectric produce a continuous potential or not??if not why??
     
  2. jcsd
  3. Aug 3, 2007 #2

    Gokul43201

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    What would be your guess, and why?
     
  4. Aug 4, 2007 #3
    well i would guess that it should not give a potential under constant load as energy is getting produced without any actual conversion hence it voilates law of conservation of energy
    but could not find anything to support my guess
     
  5. Aug 4, 2007 #4

    Gokul43201

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    There is no consumption or production of energy, in maintaining of a constant potential. It is only when you change the potential or move charges through this potential that work is done. That is not the case here.

    Anyway, you are saying that piezoelectricity itself should not be possible - not that the peizoelectric voltage be a continuous function of the applied stress. Neither of the above is true, in the general case. For the latter, think "first order phase transitions"
     
  6. Aug 4, 2007 #5
    oh sorry i forgot to say i intended to use the potential and hence change it
     
  7. Aug 4, 2007 #6
    After you appled a constant pressure to the piezoelectric crystal there will be a potential difference between two crystal surfaces. If you connect these surfaces by a wire, the electrons will flow from one surface to another. The current will stop after enough charge is transferred to compensate the original potential difference. There will be no current in the equilibrium, so no useful work can be performed after the equilibrium has been reached.

    The situation is different if the pressure applied to the crystal is variable, e.g., sinusoidal. Then an alternating current will flow through the circuit as long as the pressure is applied.

    Eugene.
     
  8. Aug 5, 2007 #7
    thanks for the explanation but i have read on wikipedia if properly applied a 2kn force can create a potential of 12500V is it usable and what is its enrgy conversion efficiency
    crystal is 1cm cube
     
    Last edited: Aug 5, 2007
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