Question

A lightweight metal ball hangs by a thread. When a charged rod is held near, the ball moves toward the rod touches the rod, then quickly "flies away" from the rod. Carefully explain what happens during each step of the process.

Answer 1

Initially there is no net charge on the metal ball.
If we take a negatively charged rod close to the rod, the free electron in the metal ball repelled by the rod and accumulates on the other side of the rod placed.
so, positive charge is induced on metal ball in the side of charged rod placed.
so, there is an attractive force between metal ball and negatively charged rod.
When the ball toches the rod negative charge flows from rod to ball.
so, metal ball gets a net negative charge. Then there will be repulsive force between the ball and negctivelyc charged rod.

so, the ball flies away from the rod.