An electromagnet is a type of magnet in which the magnetic field is produced by passing electric current through it. The magnetic strength of an electromagnet can be changed by increasing or decreasing the current or changing the core. In the above question, it is given that same electromagnet is used in all the cases. So, the magnetic strength increases with an increase in current flow and vice versa. The magnetic strength is least when current flowing is 1 A and the magnetic strength is highest when current flowing is 12 A.