An experiment was designed to investigate how changing the current and number of coils affects the strength of an electromagnet. The apparatus shown could be used by altering the current running through the coils or changing the number of coils wrapped around the iron core, then measuring the effect on the magnetic force produced. Results could show that increasing either the current or number of coils strengthens the electromagnet.

1. Investigating electromagnets
How could you use the apparatus below to investigate the
effects of changing the current and the number of coils on
the strength of an electromagnet?