Question

(a) A negatively charged iron ball (on the end of a plastic rod) exerts a strong attractive force on a penny even though the penny is neutral. How is that possible?

The electrons in the penny are ___________ by the negatively charged ball and some of these electrons move to the far side of the penny away from the ball. The result is a ____________ on the side of the penny closest to the ball and a _____________ on the side farthest away. Because of the inverse-square distance dependence of the Coulomb force, the attractive force on the positively charged side is ______________ than the repulsive force on the negatively charged side so the net force is____________.

(b) The penny accelerates toward the ball, hits it, and then is immediately repelled. What do you think causes the sudden change from an attractive to a repulsive force on contact between the penny and the ball?

Once the penny touches the iron ball some of the electrons on the ball will flow into the _________ since they are _________ by the extra electrons on the ball. This makes the penny _________ charged as well so it is then __________ by the ball.

Answer 1

Here we apply Coulomb's interaction concept as well as charging by induction concept.