Question

student is investigating what happens when a neutral metal sphere sitting on an insulated stand is touched by a negatively charged rod. The set up for the student's investigation is shown in the diagram.

image 3845826dd9f243109fa16213cd34e0d4

What will happen to the excess electrons when the negatively charged rod touches the metal sphere?

A.
The excess electrons will move from the sphere to the rod and spread out along the rod.

B.
The excess electrons will move from the rod to the sphere and spread out on the sphere.

C.
The excess electrons will move from the rod to the sphere and stay clustered in the area where the rod touches the sphere.

D.
The excess electrons will move from the sphere to the rod and stay clustered near the end of the rod that touches the sphere.

Answer 1

When a negatively charged rod touches a neutral metal sphere, the electrons will move due to the difference in charge. Specifically, since the rod has an excess of electrons, these electrons will transfer to the neutral sphere which has a deficiency of positive charge. As a result, the sphere will become negatively charged.

The correct answer is:

**B. The excess electrons will move from the rod to the sphere and spread out on the sphere.**

When the rod touches the sphere, the electrons will flow from the rod to the sphere and then distribute themselves evenly across the surface of the sphere, since charges move to minimize potential energy and spread out evenly on conductive surfaces.