Physics of Magnets

Magnets are one of the fundamental items in physics. This page is designed in order to provide a general overview of magnets and their uses as well as an in depth look into certain aspects of magnetism.

We all know certain situations where magnets are used, hanging things on a refrigerator for example. But other applications are much more useful in our society. They are used in all kinds of speakers, and in many computer parts including hard drives and floppy drives ( for recording and reading purposes). Perhaps a more common use that goes unnoticed is the magnetic strip on credit and debit cards. These have a certain magnetic makeup, that is why you are to keep them away from other magnets. Magnets are also used in many motors, in such items like a dishwasher, DVD and VHS players, and a pager or cell phone vibrator.

Magnets are all dipoles, that is they all have both a north and a south pole. No known magnetic monopoles exist. Looking at magnets from a basic point of view, opposites attract and similars 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 relationships between electricity and magnetism many of which are used in the Electromagnetic Theory. More information on the relationship between magnets and electricity can be found here.

William Scoresby used the Earth's magnetic fields to produce powerful magnets.

Michael Faraday and Joseph Henry are reported to have simultaneously discovered electromagnetic induction, which is the effect whereby the relative motion of a magnet and an electric coil produced a current.

There are three types of magnets. Permanent, temporary, and electromagnets. Permanent magnets are the most common ones. Once they are magnetized they stay so (although they can lose much of their magnetic force). They can be metals found in nature. Temporary magnets hold the properties of a magnet while in a magnetic field, but lost these properties once the field goes away. An example of this would be a paper clip that is charged and can act like a magnet for a short while. Electromagnets are wires wrapped around a metal center(usually iron).