A student rubs a rubber rod with fur, producing a negative charge on the rod. The student then touches the rod to a hollow, neutral metal sphere that stands on an insulating plastic stand. This transfers negative charges from the rod to the sphere:
Which statement best predicts what will happen to the charge, and why?
A.
It will quickly spread to the air around the sphere, because it will seek to occupy as large a volume of neutral matter as possible.
B.
It will remain at the point of contact between the rod and the sphere, because resistance in the metal prevents the charges from easily moving.
C.
It will distribute itself evenly over the surface of the sphere, because like charges repel and the sphere is a conductor.
D.
It will slowly drift to the bottom of the sphere, because the charges rapidly attach to individual atoms, making them slightly heavier than surrounding atoms.
The correct statement is C. It will distribute itself evenly over the surface of the sphere because like charges repel and the sphere is a conductor.
When the negatively charged rod is touched to the neutral metal sphere, the negative charges on the rod will repel the electrons in the metal sphere. This repulsion causes the electrons in the metal sphere to distribute evenly over its surface. Since the metal sphere is a conductor, the electrons can move freely within the material, allowing them to distribute evenly over the surface.
Option A is incorrect because the charges will not quickly spread to the air around the sphere. The charges will remain on the sphere itself.
Option B is incorrect because resistance is not a factor here. The charges will distribute over the surface due to electron repulsion, not because of resistance.
Option D is incorrect because the charges will not slowly drift to the bottom of the sphere. Instead, they will distribute evenly over the surface. The charges attaching to individual atoms and making them slightly heavier is not a relevant factor in this scenario.