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Homework Help: Mass of spherical balls after adding charges

  1. Aug 2, 2006 #1
    # Two identical spherical balls A and B are given equal amount of positive and negative charge. What is the ratio of the masses A and B now?
    a)Equal to one
    b)Greater than one
    c)Less than one
    d)May be Greater than or Less than one depending on their sizes
  2. jcsd
  3. Aug 2, 2006 #2
    Are we to assume that A is given a positive charge and B given a negative charge? Even in that case, depending upon the method by which the positive and negative charges are given, the answer could be any of a, b, or c. I don't think the answer can be d because the balls are identical. Is there more information about how to give the balls their charges?
  4. Aug 2, 2006 #3
    When an object becomes charged, it either gains or loses electrons. Since electrons are negatively charged, when an object becomes negatively charged, it GAINS electrons, and therefore mass. So, mass B gains mass.
    Similarly, when an object becomes postively charged, it loses electrons. So, mass A loses mass.

    Therefore, the ratio of the masses is now less than one.
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