Question

A student connects a battery to a wire and wraps the wire around an iron nail to produce an electromagnet. Which action should the student take to increase the number of paper clips the electromagnet can pick up?
A. He should reduce the number of turns.
B. He should decrease the current through the wire.
C. He should add another battery.
D. He should replace the iron nail with a plastic spoon.

Answer 1

Answer: C.

Adding another battery (in series) raises the voltage and therefore the current through the coil, increasing the magnetic field and allowing the electromagnet to pick up more paper clips. The other choices would weaken or remove the magnetic core (A reduces turns, B reduces current, D replaces the iron core with nonmagnetic plastic).