Finding the Net charge

  1. 1. The problem statement, all variables and given/known data

    A metal sphere has a charge of +8.0 µC. What is the net charge after 9.00 *10^13 electrons have been placed on it?


    2. Relevant equations

    q=Ne where q is the charge, N is the number of electrons, and e is given as 1.6*10^-19

    3. The attempt at a solution

    Well the problem gives us a charge, q, and the N, number of electrons, so I figure somehow I need to use this equation. I am not sure where to start though, could someone get me started? Thanks!
     
  2. jcsd
  3. Kurdt

    Kurdt 4,941
    Staff Emeritus
    Science Advisor
    Gold Member

    The electrons have a negative charge. That charge will be given by the product of the number of electrons and the charge of the electrons. Since the sphere starts with a positive charge the net charge will be the initial positive charge plus whatever charge all the electrons have. Be careful with signs here.
     
  4. I'm still having trouble...what number needs to be negative?
     
  5. Kurdt

    Kurdt 4,941
    Staff Emeritus
    Science Advisor
    Gold Member

    Electrons have a negative charge.
     
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