You have three identical metal spheres that have different initial net charges. Sphere A has a net charge of +5Q; sphere B has a net charge of ?3Q; and sphere C has a net charge of +7Q. You first touch sphere B to sphere A, and then separate them; you then touch sphere A to sphere C, and then separate them; and finally you touch sphere C to sphere B, and then separate them. What is the charge on sphere A at the end of the process?

Explanation:

Given

Sphere A has a net charge of +5 Q

Sphere B has a net charge of -3 Q

Sphere C has a net charge of 7 Q

When sphere B is touched to sphere A then charge is redistributed among the sphere such that charge on each sphere is

Now sphere A and B has charge Q

When sphere A is touched to sphere C

Net charge after removal

Now sphere A and C has 4 Q charge

Now sphere C and B is touched

Net charge on C and B is given by

At the end of process charge on sphere A is 4Q

Charge on B and C is 2.5Q