Consider three identical metal spheres, A, B, and C. Sphere A carries a charge o
ID: 1414753 • Letter: C
Question
Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of +9q. 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 B C
+9q -q 0 (given)
+4q +4q 0 (sphere A and B touched i,e 9q-q=8q/2=4q)
+2q +4q +2q (sphere A and C touched i,e 4/2=2q)
+2q +3q +3q (sphere C is touched to B i,e (4+2)/2=3q)
a) ratio of final chare on C to q is 3q/q=3
b) 9q-q+0=8q
c) 2q+3q+3q=9q