A mechanic dropped a bolt he needed to repair a car motor. He decided to make a simple electromagnet to try to attract the metal bolt. Which list of material would make the best electromagnet?
A.
metal rod for a core, copper wire, 9-volt battery
B.
glass rod for a core, copper wire, 9-volt battery
C.
plastic rod for a core, copper wire, 9-volt battery
D.
wooden rod for a core, copper wire, 9-volt battery