After
reading this section you will be able to do
the following:
Compare
the definitions of a magnetic field (from the previous page)
and an electrostatic field.
Describe
what field intensity is and how it is determined.
Explain
the "right-hand rule."
Electrostatic Field
Remember that electrons have a negative
electrostatic field surrounding them. When energy from a power
source such as a battery is applied to a circuit, making the electrons
flow through a conductor, a new type of field is developed around
the wire. This is called an electromagnetic field. You
can learn more about why this field develops in the materials
about magnetism.
As we can see in the diagram below,
the magnetic field that surrounds a current-carrying conductor
is made up of concentric lines of force. The strength of these
circular lines of force gets progressively smaller the further
away from the conductor we get. Also, if a stronger current is
made to flow through the conductor, the magnetic lines of force
become stronger. As a matter of fact, we can say that the strength
of the magnetic field is directly proportional to the current
that flows through the conductor.
Field Intensity
The term field intensity is
used to describe the strength of the magnetic field. From now
on we will use this new term to describe this field that is developed
around a conductor that is carrying electrical current.
We have determined that this magnetic
force field is a result of current flowing in a conductor. We
have also shown that the field is circular in shape. What we do
not yet know is what direction the circular field is in.
Field Direction (The Right-hand Rule)
A number of different rules have been developed to help determine the direction of the magnetic field relative to the current. “The right-hand rule” is the simplest to remember and can be used to determine
the direction of the electromagnetic field around a current carrying
conductor. With this rule when the thumb of the right-hand is pointing in the direction of current flow, the fingers will be pointing in the direction
of the magnetic field.
Review
Field
intensity is a term used to describe the strength of the
electromagnetic field.
Field
intensity is determined by the amount of electrical current
flowing in the wire.
The right-hand rule can be used to describe the direction of the electromagnetic field.
A number of different rules have been developed to help determine the direction of the magnetic field relative to the current. “The right-hand rule” is the simplest to remember and can be used to determine
the direction of the electromagnetic field around a current carrying
conductor. With this rule when the thumb of the right-hand is pointing in the direction of current flow, the fingers will be pointing in the direction
of the magnetic field.