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Radius of a Raindrop given Charge and Electric Potential

  1. Jul 15, 2013 #1
    1. The problem statement, all variables and given/known data
    A spherical rain drop carries a charge of 5×10-6 C and has a potential of 8.800×10-8 V at the surface. Find the radius of the drop.


    2. Relevant equations

    V = (kQ)/r

    3. The attempt at a solution

    I simply moved V and r to their respective spots and plugged in my numbers. I got a very large number of 5.11*10^11, so i am wondering if my units are wrong or if I am doing something else wrong. Thanks for your help!
     
  2. jcsd
  3. Jul 16, 2013 #2

    TSny

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    Hello, freddy13.

    You're right, you're getting a ridiculous answer even though your method is correct. (Your answer for the radius is more than 3 times the distance to the sun.) The value for the potential looks very suspicious. Are you sure that 10 is raised to the negative 8 power? Also, the value for the charge seems very high for a raindrop.
     
    Last edited: Jul 16, 2013
  4. Jul 16, 2013 #3
    Yeah I copied the problem exactly! It has to be something with the units that I am missing, that seems to be the only possibility!
     
  5. Jul 16, 2013 #4

    TSny

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    I agree. It must be a misprint in the statement of the problem.
     
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