PHYSICS · Single correct · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential
Problem
A plastic rod is initially neutral. After it is rubbed with wool, the rod is measured to have a net charge of −4.0×10−7C. Which statement best explains the sign of the rod’s new charge?
(a) Protons have been transferred from the wool to the rod, adding negative charge to the rod.
(b) Electrons have been removed from the rod and deposited on the wool, leaving the rod negatively charged.
(c) Electrons have been transferred from the wool to the rod, giving the rod an excess of negative charge.
(d) Rubbing polarizes the rod’s molecules so their negative ends point outward, making the rod appear negatively charged overall without any transfer of charge.