Question

While charging a metal sphere negatively by induction the electrons will flow from the ground to the sphere when it is connected to the ground. Why?

Answer 1

The ground is considered to be a huge source of electrons. Now, in charging by induction, a positively charged rod is brought near a neutral sphere such that the side of the sphere nearest to the rod gets negatively charged while the side farthest from it acquires a positive charge. If we connect the positively charged side to ground, electrons from earth will flow towards it due to fact that a potential difference is being developed.

Now, if the glass rod is removed form close to the other side of the sphere, the sphere will now acquire a net negative charged spread uniformly throughout it.