Many of us might remember playing with magnets as children. Pushing and pulling two of them using their magnetic properties was always interesting and fun. There are many important uses for magnets besides childhood fun, and these range from uses in home audio to modern medicine.
Inside the majority of speakers are magnets coupled with a coil that carries current to turn electric energy into energy that creates sound. This coil is wrapped around a bobbin that is connected to the speaker cone. The coil carries the signal that interacts with the magnetic field. The voice coil reacts to the magnetic force and moves the speaker cone while pressurizing the air inside the speaker. This process creates sound.
An important use of magnets is as the magnetized needle at the center of a compass. The magnetic field exerts force on the needle, which in turn makes the needle point to the planet's magnetic north pole, while the other end points to the magnetic south pole. In professional compasses, the needle is replaced with a magnetic bar that is glued beneath a pivoting disk.
Maglev is a transport system using magnet levitation, of which the name is derived. Designed mostly for trains, it uses large amounts of magnets to lift and propel the train at very high speeds. Using magnets this way makes for a much smoother and quieter train. In actuality, a small amount of the energy derived from the magnets is necessary to levitate the train, with most of it being employed against the air drag that comes with high-speed trains.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is used in modern medicine to image in detail the insides of the body. It uses powerful magnetic force to magnetize and align some of the body's atoms, thus causing the nuclei to give off magnetic fields that can be detected by a scanner and produce detailed images of the part of the body being scanned. Because it produces 3-D imaging, it is very useful in scanning the brain, heart and cancers.