Consider three identical metal spheres, A, B, and C. Sphere A carries a charge o
ID: 1574911 • Letter: C
Question
Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of -8q. 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? Incorrect:
. (b) What is the total charge on the three spheres before they are allowed to touch each other? Incorrect:
(c) What is the total charge on the three spheres after they have touched?
Explanation / Answer
charge of A = qA = -8q
charege of B = qB = -1q
charge of C = qC = 0
IF A and B touched
charge on B = Q = (qA+qB)/2 = -4.5q
If C is touched to A
charge on C = charge on A = Q1 = (Q+qC)/2 = (-4.5+0)/2 = -2.25q
If C is touched to B
charge on C = charge on B = Q2 = (Q1+qB)/2 = (-2.25 - 4.5)*q/2 = -3.375 q
part a
charge on C = -3.375q
part b
Qtotal = -8-1 = -9 q
part c
Qtot = (-3.375 - 3.375-2.25) = -9q