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Homework Help: How many extra electrons does the toner particle carry?

  1. Aug 2, 2010 #1
    1. The problem statement, all variables and given/known data
    A photocopier imaging drum is positively charged to attract negatively charged toner particles. Near the surface of the imaging drum, the E field has a magnitude of 1.90 × 105 N/C
    A. What must be the be the magnitude of the negative charge on a toner particle of mass 2.80 × 10 -12 kg if it is to be attracted to the drum with a force that is 10.0 times its weight?
    B. How many extra electrons does the toner particle carry?
    2. Relevant equations

    I have already figured out A with F=qe and W=mg
    That answer came out to be = 1.44E-15 C
    I cant figure out B. How many extra electrons does the toner particle carry?
    3. The attempt at a solution

    The answer here is 9.03E+3 but I dont know how that is the right answer, can someone please explain? I feel like it is probably just a formula, but i dont know it
  2. jcsd
  3. Aug 2, 2010 #2


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    Homework Helper
    Gold Member

    So you know the total charge is -1.44 x 10-15 Coulombs.

    The next thing to ask yourself is how much charge (i.e. how many Coulombs) is carried by a single electron? (You can look this up if you haven't memorized it.) :wink:

    [Edit: And welcome to Physics Forums, jbirse!]
  4. Aug 2, 2010 #3
    Thanks! I knew it was probably pretty simple, but I was just unsure of what to exactly do. thanks
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