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Essay / Physics of Magnets - 1872
Magnets are one of the fundamental elements of physics. This page is designed to provide a general overview of magnets and their uses as well as an in-depth look at certain aspects of magnetism. We all know certain situations in which magnets are used, for example to hang objects on a refrigerator. But other applications are much more useful in our society. They are used in all kinds of speakers and in many computer components, including hard drives and floppy disk drives (for recording and playback purposes). Perhaps a more common use that goes unnoticed is the magnetic strip on credit and debit cards. These have a certain magnetic composition, which is why you need to keep them away from other magnets. Magnets are also used in many motors, in items such as a dishwasher, DVD and VHS players, and a pager or cell phone vibrator. Magnets are all dipoles, meaning they all have both a north and a south pole. There are no known magnetic monopoles. Looking at magnets from a fundamental perspective, opposites attract and likes repel. Magnetic field lines always move from the north pole to the south pole, we will discuss this later. Some of the major contributors to magnets are men like Hans Christian Oersted, James Clark Maxwell, William Scoresby, Michael Faraday, and Joseph Henry. Hans Christian Oersted Experiment with a wire carrying a current and a compass led to much of what we know about magnetic fields. James Clark Maxwell discovered the relationships between electricity and magnetism, many of which are used in electromagnetic theory. For more information on the relationship between magnets and electricity, click here. William Scoresby used the Earth's magnetic fields to produce powerful magnets. Michael Faraday and Joseph Henry are said to have simultaneously discovered electromagnetic induction, which is the effect by which the relative movement of a magnet and an electric coil produces a current. There are three types of magnets. Permanent, temporary and electromagnets. Permanent magnets are the most common. Once magnetized, they remain that way (even though they may lose much of their magnetic force). These may be metals found in nature. Temporary magnets retain the properties of a magnet when in a magnetic field, but lose these properties once the field is gone. An example of this would be a paper clip that is charged and can act like a magnet for a short time. Electromagnets are wires wrapped around a metal center (usually iron).