Question

In Figure 18.8 the grounding wire is removed first, followed by the rod, and the sphere is left with a positive charge. If the rod were removed first, followed by the grounding wire, would the sphere be left with a charge? Account for your answer.

Answer 1

If the charged rod is removed before the grounding wire, the sphere will not retain a net charge because any excess charge will flow back to ground. Only if the grounding wire is removed while the rod is still present does the sphere retain an excess charge.

Step-by-step explanation:

If the grounding wire is removed after the charged rod is taken away, the sphere would be left with no net charge. This is because during the process of charging by induction, if the rod is removed first, any excess charge on the sphere would have the opportunity to redistribute evenly across its surface. Since the sphere was initially neutral and the grounding wire is still connected, the excess charge would flow to the ground, effectively bringing the sphere back to a neutral state.

On the other hand, as described in your references, if the grounding wire is removed first while the charged rod is still present, the sphere retains an excess of electrons. This happens because by breaking the ground connection while the sphere is still influenced by the nearby positive charge of the rod (which repels the electrons), the redistributed electrons are trapped on the sphere, thus leaving the sphere negatively charged. When the positive rod is finally removed, the sphere remains negatively charged because the extra electrons have no path to escape.

Answer 2

In Figure 18.9, the ground wire is first removed, then the rod. This leaves a positive charge on the sphere. If you remove the rod first and then remove the ground wire, there will be no charge left on the sphere. When the rod is removed, the repulsive force caused by the presence of the rubber rod no longer exists. As the wire is still attached, free electrons enter the sphere from the ground until the sphere is neutral again.