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

ID: 2273584 • Letter: C

Question

Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of +7q. 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) After A touches B each will have -q/2 charge
After C touches A each will have -q/4

After C touches B each will have -3q/7

b) Before the net charge is -2q + q = -q

c) after touching -3q/7 - 3q/7 -q/4 = -q