Question

A plastic rod that has been charged to -21 nc touches a metal sphere. afterward, the rod's charge is -8 nc. (a) what kind of charged particle was transferred between the rod and the sphere, and in which direction? that is, did it move from the rod to the sphere or from the sphere to the rod?

Answer 1

The rod transferred negatively charged particle to the metal sphere. The rod becomes less negatively charged than it was originally (originally it was charged to -21 nc, now it has -8, and -8>-21), so it must have moved 13 nc of negative charge to the sphere.