Range Rover County LWB (LH) V8-4.2L (1993)
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In this illustration, one side of the loop will be a north pole and the other side will be a south pole. By increasing the number of loops, the magnetic field
will be greatly increased. By winding the loops or coils on a core of soft iron, the field is further intensified.
RIGHT HAND RULE
The direction of the magnetic field can be determined by using the RIGHT HAND RULE. If you place your right hand over the conductor with your
thumb pointing in the direction of current flow (from "+' to "-," or towards "-"), your curled fingers will show the direction of the magnetic field and the
lines of force.
NOTE: For the Electron Theory, where current flows from negative (-) to positive (+), this is also known as the LEFT HAND RULE.
ELECTROMAGNETIC INDUCTION
The process by which a magnetic field causes current to flow in a conductor is a process that can be reversed. Under proper conditions, a magnetic field
can cause current to flow in a conductor. This is called inducing or generating electricity by magnetism.
To induce voltage in a conductor, it is necessary to have relative motion between the conductor and the magnetic field, either by:
1. A magnetic field moving across a stationary field, as in an AC generator (Alternator).
2. A magnetic field building or collapsing across a stationary conductor, as in an ignition coil.
DC (DIRECT CURRENT) VS. AC (ALTERNATING CURRENT)
Electron flow in DC (direct current) moves in one direction only. Since we adhere to the Conventional Electrical Theory in automotives, DC current flow
is from positive (+) to negative (-). The battery is a good example of a source of DC voltage. DC voltage does not have to remain absolutely constant and
it's value can change.
When automobiles had relatively simple low power electrical systems, DC voltage produced by generators provided an adequate current supply.
AC (alternating current) is electricity that changes its direction at regular definite time intervals or frequency. This AC current changes its direction
according to the Law of Sines. As shown in the graph, the current first increases to its peak, then decreases through zero. It changes its direction,
increasing to its peak, then decreasing back through zero. This process continues to form a frequency or Sine Wave. The unit of frequency we use to
measure the speed at which the current changes direction is called Hertz (Hz). In automobiles, AC current is produced by AC generators (Alternators)
and, through the use of diodes, is changed to DC.