# Finding the charge

Two fixed, non-conductive, isolated rings of radii $$25~\mbox{cm}$$ are electrified and brought close to each other so that they are parallel. The distance between them is $$1~\mbox{m}$$. You know that one of them has a charge of $$1~\mbox{nC}$$ evenly distributed on it, but you are not sure about the other. In order to find out what's the charge on the other, you take a charged ball and move it across the axis of the rings until you find its equilibrium position. You measure where that is and get that the equilibrium position is $$25~\mbox{cm}$$ from the center of the ring with the known charge. What's the charge in nC of the second ring?

Details and assumptions

• The second ring also has evenly distributed positive charge on it.
×