• Solenoid ∘ It is a long straight coil of wire that can be used to generate a nearly uniform magnetic field similar to that of a bar magnet. ∘ When the electric current passes through the coil, it creates a relatively uniform magnetic field inside the coil. ∘ The soft iron inside the coil makes the magnetic field stronger because it becomes a magnet itself when the current is flowing. It is then called an electromagnet.