Question

Which change would result in a stronger electromagnet?

A) Reducing the number of batteries
B) Increasing the voltage of the battery
C) Substituting another metal for the iron core
D) Decreasing the number of coils around the iron core.

Answer 1

I'd say B.) Increasing the voltage of the battery.

Answer 2

From that particular list of choices, 'B' is the only one that will do that job.