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Consider three identical metal spheres, A, B, and C. Sphere A carries a charge o

ID: 2270602 • Letter: C

Question

Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of +3q. Sphere B carries a charge of -q. Sphere C carries no net charge. Spheres A and B are touched together and then separated. Sphere C is then touched to sphere A and separated from it. Lastly, sphere C is touched to sphere B and separated from it. (a) What is the ratio of the final charge on sphere C to q? What is the ratio of the final total charge on the three spheres to q (b) before they are allowed to touch each other and (c) after they have touched?

Explanation / Answer

A and B each have +(1) q after they touch.

Then C and A each have (.5)q after they touch

Then C and B each have (3/4) q after they touch.

Total charge at start = 3q -q = 2Q

Total charge at end = (1/2)q +(3/4)*2q=2q