What Makes a Magnet?
All magnets have north and south poles. Opposite poles attract, same poles repel. Magnets create invisible magnetic fields around them. These fields can push and pull on other magnets and certain metals (iron, nickel, cobalt).
Earth Is a Giant Magnet
Earth's iron core acts like a bar magnet, creating the magnetic field that protects us from solar radiation. That's why compass needles point north — they're following Earth's magnetic field lines.
Electromagnets
When electric current flows through a coil of wire, it creates a magnetic field. Increase the current or the number of coils, and the magnetic field gets stronger. Electromagnets are in motors, speakers, MRI machines, and particle accelerators.
Applications
Electric motors use electromagnets to convert electrical energy to motion. Generators do the reverse — motion to electricity. Magnetic resonance imaging (MRI) uses powerful magnetic fields to image inside your body without radiation.