Current flow through any conductor creates a magnetic field. Whenever electrical current is flowed through copper wire, a magnetic field is created surrounding the wire. This effect can be observed by passing a copper wire through which current is flowing lengthwise over a compass needle. The compass needle will deflect from its north-south alignment when this occurs. Any magnetic field created by electrical current flow is known as electromagnetism. Study of the behavior of electromagnetic fields has proven the following:
• Magnetic lines of force do not move when the current flowing through a conductor remains at a constant. When current flowed through the conductor increases, the magnetic lines of force will extend further away from the conductor.
• The intensity and strength of magnetic lines of force increase proportionally with an increase in current flow through a conductor. Similarly, they diminish proportionally with a decrease in current flow through the conductor.
• A rule called the right-hand rule is used to indicate the direction of the magnetic lines of force:
The right hand should enclose the wire with the thumb pointing in the direction of conventional current flow (positive to negative), and the fingertips will then point in the direction of the magnetic lines of force.