• Figure 3A, the charges are opposite, X ball is positive and Y ball is negative, and they are at an equal distance apart. They will attract each other.
• Figure 3B shows that the charge on X ball has been doubled to +2, thus the ball is bigger and it doubles the electric force it exerts. Y ball is still negative, but the force on both charges are doubled. They will attract each other.
• Figure C shows that both X ball and Y ball have a positive charge. This would cause them to repel each other because like charges repel.