Magnetism is a force that acts at a
distance and is caused by a magnetic field. This force
strongly attracts ferromagnetic materials such as iron,
nickel and cobalt. In magnets, the magnetic force
strongly attracts an opposite pole of another magnet and
repels a like pole. The magnetic field is both similar
and different than an electric field.
Questions you may have include:
-
What is a magnetic field?
-
What is a magnetic force?
-
How do magnetic and electric fields
compare?
Magnetic field
A magnetic field consists of imaginary
lines of flux coming from moving or spinning
electrically charged particles. Examples include the
spin of a proton and the motion of electrons through a
wire in an electric circuit.
What a magnetic field actually consists
of is somewhat of a mystery, but we do know it is a
special property of space.
Magnetic field or lines of flux of a
moving charged particle
The lines of magnetic flux flow from one
end of the object to the other. By convention, we call
one end of a magnetic object the N or North-seeking pole
and the other the S or South-seeking pole, as related to
the Earth's North and South magnetic poles. The magnetic
flux is defined as moving from N to S.
Although individual particles such as
electrons can have magnetic fields, larger objects such
as a piece of iron can also have a magnetic field, as a
sum of the fields of its particles. If a larger object
exhibits a sufficiently great magnetic field, it is
called a magnet.
Magnetic force
The magnetic field of an object can
create a magnetic force on other objects with magnetic
fields. That force is what we call magnetism.
When a magnetic field is applied to a
moving electric charge, such as a moving proton or the
electrical current in a wire, the force on the charge is
called a Lorentz force.
When two magnets or magnetic objects are
close to each other, there is a force that attracts the
poles together.
Force attracts N to S
Magnets also strongly attract
ferromagnetic materials such as iron, nickel and cobalt.
When two magnetic objects have like
poles facing each other, the magnetic force pushes them
apart.
Force pushes magnetic objects apart
Magnets can also weakly repel
diamagnetic materials.
Magnetic and electric fields
The magnetic and electric fields are
both similar and different. They are also inter-related.
Just as the positive (+) and negative
(-) electrical charges attract each other, the N and S
poles of a magnet attract each other.
In electricity like charges repel, and
in magnetism like poles repel.
The magnetic field is a dipole field.
That means that every magnet must have two poles.
On the other hand, a positive (+) or
negative (-) electrical charge can stand alone.
Electrical charges are called monopoles, since they can
exist without the opposite charge.
Magnetism is a force that acts at a
distance and is caused by a magnetic field. The magnetic
force strongly attracts an opposite pole of another
magnet and repels a like pole. The magnetic field is
both similar and different than an electric field. |