Consider three identical metal spheres, A, B, and C. Sphere A carries a charge o
ID: 1523146 • Letter: C
Question
Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of -2q. Sphere B carries a charge of -7q. 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
When sphere A and B are touched together the total charge is redistributed equally to both
Charge on A : -2q
Charge on B : -7q
Total charge : -9q
Charge on A and B when they are touched
A : - 4.5 q
B : - 4.5 q
Sphere C is toched to sphere A
Charge on C : 0
Charge on A : - 4.5q
Total charge on A and C : - 4.5 q
when thry touch charge is equally distributed
Charge on A : - 2.25q
Charge on C : - 2.25q
(a) Thus sphere C ends with charge - 2.25 q
(b & c) Total charge will always be constant. Thus total charge on 3 spheres before and after touching
A+B+C = - 9q