Question

During an experiment in physics lab, you rub a rubber rod with fur, which ends up leaving a negative charge on the rubber rod and a positive charge on the fur. To your surprise, you find that the charged rubber rod is able to attract small Styrofoam pellets. Must the pellets be charged? With the equipment you already have, how can you collect more data in support of or in opposition to your conclusion?

Answer 1

no need of the styrofoam balls intially charged. In this case intially the styrofoam balls are neutral. when a rubber rod which is negative is placed near the styrofoam balls then charge redistribution happens in the balls.

it mean positive charges in the balls moves near to the rubber rod where as the negative charges moves to the other end of the balls so the center of both positive and negative charges are not coincide and leads to attract to the rubber rod.