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Surface Charge/Electric Field

  1. Jul 9, 2008 #1
    Space vehicles traveling through Earth's radiation belts can intercept a significant number of electrons. The resulting charge buildup can damage electronic components and disrupt operations. Suppose a spherical metallic satellite 0.9 m in diameter accumulates 2.2 µC of charge in one orbital revolution.
    (a) Find the resulting surface charge density.
    (b) Calculate the magnitude of the electric field just outside the surface of the satellite, due to the surface charge.

    2. Relevant equations
    a. Looking at the units I need the answer in, I assumed that the surface charge density is charge/area or C/m^2.
    for this problem that would be Q /(pie x r^2) or 2.2e^-6C / (pie x .45^2)

    So I solved and got 2.2e-6/.6361725124 = 3.458e-6

    This is not the right answer - I can't find part a which should be easy - a little help please.
  2. jcsd
  3. Jul 9, 2008 #2


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    Gold Member

    The satellite is spherical in shape.

    The area you have is the area of a circle, not the surface area of a sphere...
  4. Jul 9, 2008 #3
    wow - thanks - I knew there was something obvious I was over looking
  5. Jul 9, 2008 #4


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    No problem. Glad I could help.:smile:
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