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Capacitance -Problem-

  1. Jun 20, 2009 #1
    As a person moves in an environment dry, electric charge accumulates in the body. Since the body is in high voltage, positive or negative, can download by visible sparks or shocks. Consider a human body and separate the soil, with typical capacitance of 150pF.

    (a) Load that the body produces a potential of 10,0kV ?

    (b) Sensitive electronic equipment can be destroyed by electrostatic discharge of a person. A device can be destroyed by a discharge that releases an energy of 250x10^{-6}J. This corresponds to the voltage on the body ?
     
  2. jcsd
  3. Jun 20, 2009 #2

    negitron

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    Sounds like homework to me. How would YOU go about solving these problems?
     
  4. Jun 21, 2009 #3
    I do not understand the problem. What should I calculate?
     
  5. Jun 21, 2009 #4

    Redbelly98

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    (a) I am just guessing, but I think "load" means charge. So calculate the charge.
     
  6. Jun 21, 2009 #5
    Yes. I also think it load is charge
     
  7. Jun 21, 2009 #6

    Redbelly98

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    Have you reviewed the equations that involve capacitance? That is where to start.
     
  8. Jun 21, 2009 #7

    negitron

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    Specifically, you want to find the equation which relates capacitance, charge and voltage. And the equation which relates charge, voltage and energy.
     
  9. Jun 23, 2009 #8
    I think:

    a) Q = C.V

    Q = (150x10^{-12})x(10x10^{3})
    Q = 1.5x10^{-6} coulomb


    Alternative (b) I do not understand
     
  10. Jun 23, 2009 #9

    berkeman

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    Correct equation and calculation for (a).

    Now, for (b), you need an equation that relates capacitance, voltage and the energy stored on that capacitance...
     
  11. Jun 25, 2009 #10
    I find
    (b) U = 1/2 * C * V^2
    V = 1825,74 V
     
  12. Jun 25, 2009 #11

    Redbelly98

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    Looks good! Though we really only know that number to 2 significant figures.
     
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