Consider three identical metal spheres, A, B, and C. Sphere A carries a charge o
ID: 1532354 • Letter: C
Question
Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of -6q. Sphere B carries a charge of -1q. 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. Last, sphere C is touched to sphere B and separated from it. For the following questions, express your answers in terms of q.
(a) How much charge ends up on sphere C?
(b) What is the total charge on the three spheres before they are allowed to touch each other?
(c) What is the total charge on the three spheres after they have touched?
Explanation / Answer
a) When A and B are touched
A carries -6q charge and B carries -1q charge.
When they are touched, the net charge on them become -6q + (-1q) = -7q
When they are separated, - 7q is divided among them
So each A and B have got - 3.5q
When C is touched to A.
A has -3.5 q and C has 0q
Once they are touched and separated, total charge - 3.5q is divided among them
Both A and C has now -1.75q charge
When C is touched to B
C has -1.75 q and B has - 3.5 q
Total charge = - 1.75q + (-3.5q) = -5.25q is divided among them equally.
Both B and C has got - 2.625q charge
a) - 2.625 q on C
b) Total charge before = - 6 q + (-1 q) = -7 q.
c) Total charge after = - 2.625 q + (- 2.625 q) + (-1.75 q)
= - 7 q.