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Homework Help: Electric field strength of van de graff generator

  1. Jun 9, 2012 #1
    A VDGG is used to produce a large PD. The dome of the generator has a radios of 0.15m. It is charged and gets a PD between the dome and the earth of 75kV.

    The charged stored on it is : 5.0 x 10-6C

    Answer: Use of E = Q/4∏εr0. 3.0 x 105

    My attempt: E = kQ/r2 = 8.99 x 109 x 5.0 x 10-6 / 0.152 = 2.00 x 106

    I get the provided answer if I don't square the 0.15. It also seems to be a potential print error as r is not squared in their equation aswell as having a 0 as a sub-ponent(opposite of exponent?)... Could anyone share any light on this?

    Much appreciated :)
  2. jcsd
  3. Jun 9, 2012 #2
    Uh what is the question?
  4. Jun 9, 2012 #3
    Sorry, long day!

    I get an answer of 2.0 x106, while the provided answer is 3.0 x 105.
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