Question

A group of students were learning about the transfer of charge. First the students rubbed the glass rod with a piece of silk fabric, which gave the rod a positive charge. Then the students touched the glass rod to the surface of the conducting metal sphere.



image


Which of the following describes the charge on the conducting sphere and the glass rod when the glass rod is removed from contact with the sphere?



A.
The glass rod will transfer positive charges to the conducting metal sphere resulting in both the glass rod and the conducting sphere having a positive charge.

B.
The glass rod will transfer positive charges to the neutral conducting sphere resulting in the glass rod becoming neutral and the conducting sphere having a positive charge.

C.
The neutral conducting sphere will transfer negative charges to the glass rod resulting in the conducting sphere having a negative charge and the glass rod having a positive charge.

D.
The neutral conducting sphere will transfer negative charges to the positively charged glass rod resulting in the conducting sphere having a positive charge and the glass rod becoming neutral.

Answer 1

D.

When the positively charged glass rod touches the neutral metal sphere, electrons (negative charges) flow from the conductor into the rod to neutralize its positive charge. The conductor therefore loses electrons and becomes positively charged; the rod becomes neutral (or less positive). Positive charges (protons) do not move in the solids, so the transfer is of electrons from sphere to rod.