Answer:
B. Electrons moving freely through a copper wire.
Step-by-step explanation:
- A conductor is a material which can conduct an electric current, which means it is a material where electrons are free to move through
- An insulator is a material in which electrons are not free to move, so they stuck at one place, and no electric current can pass through it
Let's now analyze each option:
A. a rubber shoe sole with electrons stuck to the bottom. --> this is an insulator, because the electrons are stuck at one place
B. Electrons moving freely through a copper wire. --> this is a conductor, since electrons are moving freely through the wire, so an electrical current is produced
C. a balloon with a small region of negatively charged electrons. --> this is still an insulator, since the electrons are stuck in one region
D. A rubber coating preventing electrons from moving from a radio cord to your hand. --> this is an insulator, since the rubber coating is preventing electrons from moving