Consider three identical metal spheres, A, B, and C. Sphere A carries a charge o
ID: 2034028 • 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
Law of Conservation of Charge is applicable here;
a) A and B are touched together and then separated
Qa = 4q, Qb = 4q;
Sphere C is then touched to sphere A and separated from it
Qc = 2q, Qa = 2q
finally sphere C is touched to sphere B and separated from it
Qc = 3q, Qb = 3q
therefore final charge on A, B and C sphere is;
Qa = 2q , Qb = 3q and Qc = 3q. (you can find the ratio)
a) ratio of the final charge on sphere C to q
Qc/q = 3q/q = 3.
What is the ratio of the final total charge on the three spheres to q
Q = Qa + Qb + Qc =8q
Q/q = 8q/q = 8.
b) before they are allowed to touch each other
Qa/q = 9q/q = 9;
Qb/q = - q/q = -1
Qc/q = 0
c) they have touched
Qa/q = 2q/q = 2;
Qb/q = 3q/q = 3;
Qc/q = 3q/q = 3.