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Homework Help: Help (Electrostatic/electric shock)

  1. Apr 20, 2005 #1
    here's a problem that I am currently working on. I know the theory, but I'm not quite sure how to start this particular problem:

    "Thomas was crawling around on the rug. When he reached for a metal truck, a prominent spark lasting 5mmsec appeared between his fingertip and the object. His fingertip was about 2 mm from his toy. His finger burnt (the area of the burned region was of 10^-4 m^2)

    On that day, the air was cold and dry causing it to become conducting when the electric field reached 3*10^6 N/C."

    My question is, how you I determine the charge on the child's fingertip?
    How do I estimate the resistance of the dry air between the toy
    truck and the child's fingertip? (I just would like to know how to start this problem.. you don't have to do the entire thing)

    Thank you in advance
  2. jcsd
  3. Apr 21, 2005 #2
    First you determine the voltage that gives a 2 mm spark (the breakdown field strength is given, but in other units than V/m).

    Then you equate the energy when a charge Q goes through the calculated potential difference with the energy needed to produce such a burn (I do not know how to estimate that - are there more things given?).
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