Work Step by Step
The attraction occurs because of induced charge – see Figure 21.7b for the situation. The positively charged rod attracts electrons to the closer side of the metal sphere. These nearby electrons are strongly attracted to the rod, compared to the weak repulsion between the glass rod and the positive charges within the metal sphere. After they touch, electrons flow out of the metal ball to partially neutralize the charged glass rod, leaving a net positive charge on the ball. The rod and sphere will each have the same positive charge, and like charges repel.