A certain electroscope is charged until it holds $0.10\text{mC}$ of negative charge. Have electrons been added to the electroscope, or removed from it, and how many?

Figure 22.8 showed how an electroscope becomes negatively charged. The leaves will also repel each other if you touch the electroscope with a positively charged glass rod. Use a series of charge diagrams to explain what happens and why the leaves repel each other.

A plastic rod that has been charged to −15 nC touches a metal sphere. Afterward, the rod's charge is −10 nC.b. How many charged particles were transferred?

3.5×10^10 electrons are added to a plastic rod by rubbing it with wool. What is the charge on the rod?

A glass rod that has been charged to +12 nC touches a metal sphere. Afterward, the rod’s charge is +8.0 nC.b. How many charged particles were transferred?

A plastic rod that has been charged to −15 nC touches a metal sphere. Afterward, the rod's charge is −10 nC.a. What kind of charged particle was transferred between the rod and the sphere, and in which direction? That is, did it move from the rod to the sphere or from the sphere to the rod?

Figure 22.8 showed how an electroscope becomes negatively charged. The leaves will also repel each other if you touch the electroscope with a positively charged glass rod. Use a series of charge diagrams to explain what happens and why the leaves repel each other.