A metal sphere is placed on an insulating stand. A negatively charged rod is brought close to it. If the sphere is earthed and the rod is taken away, what will be the charge on the sphere?
A. The sphere will remain neutral. B. The sphere will have a net negative charge. C. The sphere will have a net positive charge. D. The sphere will become polarized
Correct Answer: C
Explanation
When a negatively charged rod is brought close to a metal sphere, the free electrons in the sphere are repelled from the rod and move to the other end of the sphere. This creates a region of positive charge on the side of the sphere closest to the rod, and a region of negative charge on the opposite side. The process of charge distribution stops when the net force on the free electrons inside the metal is equal to zero.
If the sphere is then earthed, the free electrons will flow from the sphere to the ground, leaving the sphere with a net positive charge.
