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

In the figure, r1 = 2 and r2 = 8 cm. Before the conducting spheres are connected by the wire a charge of 6.0×10-7 C is placed on the smaller sphere while the larger sphere is uncharged. Calculate the charge on the smaller sphere after the wire is connected. Assume that the separation of the spheres is very large compared to their radii.

(Figure shows a small sphere on the left with a wire attaching it to a larger sphere on the right)

2. Relevant equations

3. The attempt at a solution

When the spheres are wired together the charge travels to the larger one also, and is now spread evenly along the surface of both spheres. The charge on the smaller one should be the fraction of the surface area of the small sphere over the total surface area of both spheres times the total charge, q.

q * 4pir1^2 / (4pir1^2 + 4pir2^2) = qr1^2 / (r1^2 + r2^2).

--Instructor reply: "The charge distribution is not a simple function of the ratio of the surface areas. The key for this problem is that the wire means that the skins for both spheres will be at the same electric potential."

--- me, now: I don't know what to do... T_T

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# Two Wired Up Metallic Spheres

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