When electrified rods are brought near light objects the rods induce opposite charges on the near surfaces of the objects and similar charges move to the further side of the object.

The centres of the two types of charges are slightly separated. We know that opposite charges attract while similar charges repel.

The magnitude of force depends on the distance between the charges and in this case the force of attraction is greater than the force of repulsion.

As a result the particles like bits of paper or pith balls, being light, are pulled towards the rods.