(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

2. The potential at the center of a circle of radius 90 cm with three charges of +1 nC, -2 nC, and +2 nC placed 120 degrees apart on the circumference is:

a) 8.0 V

b) 12

c) 16

d) 9

Answer: d

6. The electrostatic energy stored in the electric field around a conducting sphere of radius R carrying a net charge of Q is:

a)[tex] kQ^{2} / 2R [/tex]

b)[tex] kQ^{2} / 4R [/tex]

c)[tex] kQ^{2} / 2R^{2} [/tex]

d) [tex]kQ^{2} / 4R^{3} [/tex]

Answer: a

2. Relevant equations

3. The attempt at a solution

2) [tex] V = \frac{k}{0.9}*10^{-9}*(1-2+2) = 10 V[/tex]

That obviously doesn't agree with the answer.

6) I was thinking of doing U = qV, and then using kq/r for the potential of a sphere, except then I don't have a point charge to multiply by. If i multiply by q, I just get kq^2 / r, which isn't the right answer.

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# Homework Help: Potential Problems

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