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Homework Help: Charge density higher on sharp ends

  1. Feb 15, 2012 #1
    1. The problem statement, all variables and given/known data
    Two charged conducting spheres of radii a and b are connected to
    each other by a wire. What is the ratio of electric fields at the surfaces
    of the two spheres? Use the result obtained to explain why charge
    density on the sharp and pointed ends of a conductor is higher
    than on its flatter portions.

    2. Relevant equations

    3. The attempt at a solution
    first part can be done by using the fact that electric field outside the sphere is given by E = q / 4(pi)(e_0)r^2
    some confusion at second one
  2. jcsd
  3. Feb 15, 2012 #2


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    You don't know the charge on each sphere, so E = q / (4(π)(ε0)r2) will not get you anywhere until you do know those relative charge values. (Also, parentheses are important.)

    The spheres are connected by a wire so their surfaces are at the same potential. Use that to find the relative charge on the spheres.
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