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Homework Help: Help equation to find # of electrons

  1. Mar 5, 2008 #1
    [SOLVED] Help equation to find # of electrons

    1. The problem statement, all variables and given/known data
    Just as you touch a metal door knob, a spark of electricity (electrons) jumps from your hand to the knob. The electric potential of the knob is 2.0*10^4 V greater than that of your hand. The work done by the electric force on the electrons is 1.5*10^-7 J. How many electrons jump from your hand to the knob?

    2. Relevant equations
    1e = 1.6*10^-19 Coulombs

    3. The attempt at a solution
    1.5E-7 / 2E4 = 7.5E-12
    7.5E-12 / 1.6E-19 = 4.7E7 Electrons.
    Last edited: Mar 5, 2008
  2. jcsd
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