Chapter 23, Problem 18PQ

An electrophorus is a device developed more than 200 years ago for the purpose of charging objects. The insulator on top of a pedestal is rubbed with a cloth, such as wool (Fig. P23.18A). A conductor is placed on top of the insulator, and the conductor is connected to ground by a conducting wire (Fig. P23.18B). (The conductor has an insulating handle, so charge cannot be transferred between the person and the conductor.) The conductor is then removed (Fig. P23.18C). The conductor may then be used to transfer charge to other objects. If the insulator’s charge after being Ribbed with the wool is negative, what is the charge of the conductor when it is removed?