The discussion below flows on from a thread i created called "Why Electricity flows". This thread discusses magnetic fields, and how they are created
naturally, and also artifically by through a mechanism called Electromagnetic Induction. This thread is design to encourage discussion and debate
from members as i certainly dont proclaim to be an expert in the areas of magnetism.
The transmission of electric current (electricity) in a electrical conductor will produce a symertical magnet field . The link below shows numerous
examples of magnetic field lines around coil shaped conductors.
And an example of transmission of electric current through a straight line conductor.
Electric current is electrons in motion and the term conductor describes a metal material which possesses very low resistance. This characteristic of
low resistance allows electric current (electrons in motion) to flow freely. The most typical material used for conductors is Copper and Aluminium as
these have the highest conductive property of the non-precious metals. Think of conductivity as the opposite to resistance in that conductivity
allows free movement of electrons through conductors in wires, cables etc.
This focus of this thread of course is about magnetic fields and how they are produced. To establish the setting correctly in this thread it is
important to repeat what my lecturer years ago said about magnetic fields. He said we ".....know a substantial lot about electricity and electric
current but nothing about is magnetism..." Basically what he was getting at without saying it explicitly is the phenomenon we know as Magnetism is a
Oh sure Science has worked out and understands the characteristics of magnetism such as the existance of magnetic lines of force between north and
south poles on Magnets, and creation of magnetic lines of force by passing electric currents through a conductors, but try to go deeper than this and
its entering the cerebal space of theories and ideas as to describe the nature of magnestism.
So what is the difference between terms used Magnetism and Magnetic field?
The Magnetism is a force where objects are are attracted or repelled from eachother. In nature we see natural magnetism exhibited by Ferromagnetic
materials an the most common of these are iron, nickel and cobalt. A permanent magnet is formed from Ferromagnetic materials or is a material that
that can be magnetized in the presence of Ferromagnetic materials.
Magnetic Fields are produced by either Magnetic materials or Electric currents. The magnetic field is a Vector field. The magnetic field which symbol
is given in physics & engineering as B is defined in terms of a force acting on a electric charge which is moving through the field. The force on the
electric charge will have both a magnitude and direction for any location point within the field. In this context the force on an electric charge
passing through a magnetic field is a Vector quantity. Vector quantities therefore have both quantity and direction, compared alternatively to Scalars
which have only quantity.
The link below provides a diagram and a mathematical expression for magnetic force acting on a moving charge in the magnetic field.
This now brings me to discussing Electromagnetic induction. This is basically the mechansim for which causes magnetic fields to be produced from flow
of electric current in conductors.
The basic principal of Electromagnetic induction is observed in instances of when physically moving a conductor through the magnetic field. The
movement of the conductor in a perpendicular direction to the direction of the magnetic field will induces an electric current through the conductor.
The term perpendicular is referring to that the direction of conductor movement and direction of the magnetic field are displaced at ninety degrees
to eachother (just think of the floor of your house meeting with the wall, these two planes are displaced at ninety degrees to eachother).
The effect of reducing the displacement angle between the conductor direction of movement against the magnetic field direction will cause a
corresponding reduction in the amount of electric current induced to flow in the conductor. If the conductor is moving in the same direction the
magnetic field is pointing in this means that no electric current will be travelling through conductor. Therefore the effect of induction is at its
maximum when a conductor is moving in a direction which is perpendicular ( a ninety degrees) to the direction of the magnetic field.
An interesting physical phenomena of the conductor moving the magnetic field is it experiences a magnetic force. The force is perpendicular to both
the direction of the magnetic field and electric current passing through the conductor. The link below shows the relationship between the Magnetic
field (B), the velocity of the electric current (V) and the magnetic force (F).
This relationship between B, V, and F is well undestood in design of electrical rotating machinary. Remember in engineering analysis the direction of
electrical current is denotated in the opposite direction to that the electrons are flowing, hence the charge symbol q in the diagram is designated
as (+) positive.
edit on 10-11-2012 by AthlonSavage because: (no reason given)