Question

A positive rod is placed to the left of sphere A, and the spheres are separated.

An illustration of two spheres on rods touching each other labeled A and B and are neutral. There is a positively charged rod brought next to the sphere labeled A and it is negative. Sphere B has positive charges far from the rod.

Which best describes the spheres?

Sphere A is negative and sphere B is positive because protons from sphere A are attracted to the rod and move to sphere B.
Sphere A is negative and sphere B is positive because electrons from sphere B are attracted to the rod and move to sphere A.
Sphere A is positive and sphere B is negative because electrons from the rod move to sphere B and protons then move to sphere A.
Sphere A is positive and sphere B is negative because protons move from sphere B to the rod and also to sphere A.

Answer 1

"Sphere A is negative and sphere B is positive because electrons from sphere B are attracted to the rod and move to sphere A."

Reason: in conductors only electrons move. A positive rod induces electrons to flow toward sphere A (away from B) while the spheres are touching, leaving sphere B electron‑deficient (positive). Protons in the metal do not move.