A solenoid wrapped around a bar of iron or other ferromagnetic material forms what?
compress
impoundment
compass
electromagnet
Solenoids are the basis of electromagnets. An electromagnet is a solenoid wrapped around a bar of iron or other ferromagnetic material (see Figure below ). The electromagnetic field of the solenoid magnetizes the iron bar by aligning its magnetic domains. The combined magnetic force of the magnetized iron bar and the wire coil makes an electromagnet very strong. In fact, electromagnets are the strongest magnets made. Some of them are strong enough to lift a train. The maglev train described earlier, in the lesson "Electricity and Magnetism," contains permanent magnets. Strong electromagnets in the track repel the train magnets, causing the train to levitate above the track.