An uncharged conducting sphere is mounted on an insulating stand. A student brings a negatively charged rod close to the left side of the sphere, without making contact.
While holding the rod in this position, the student connects an Earth wire to the right side of the sphere, as shown in the diagram below.
With the rod still in position, the Earth wire is disconnected. Finally, the charged rod is removed.
Which of the following correctly describes the direction of charge flow through the Earth wire during the grounding step, and the final net charge on the sphere?
Electrons flow from the Earth to the sphere; the sphere is left with a net negative charge.
Positive ions flow from the sphere to the Earth; the sphere is left with a net negative charge.
Electrons flow from the sphere to the Earth; the sphere is left with a net positive charge.
Protons flow from the Earth to the sphere; the sphere is left with a net positive charge.