Question

Sphere A has a charge of +2 x 10 to the power of -6 coulomb and is brought into contact with a similar sphere, B which has a charge of -4 x 10 to the power of -6 coulomb. After it is separated from Sphere B, Sphere A will have a charge of
A) +2 x 10 to the -6 power C
B) -1 x 10 to the -6 power C
C) +6 x 10 to the -6 power C
D) -2 x 10 to the -6 power C

* please explain as I'm lost, thank you! :)

Answer 1

When sphere A and B are brought in contact and separated, charge on each sphere becomes [2x10^-6 + (-4x10^-6)]/ 2 = -1x10^-6 C.

That is, charge is equally separated and is the average of charges on both spheres. The reason behind equal charge on both spheres after separation is, when they are kept in contact, their potential difference becomes same.