Electricity and Magnetism

Magnetism’s ability to serve mankind especially lies in its relationship to electricity. Remember that the minute electrical current within the atom causes magnetism in the first place. In fact, magnetism and electricity are so closely related that each one causes the other. How is this so?

Electricity flowing through a wire causes that wire to become magnetized. No, the wire will not attract other metals because the magnetic field surrounds the wire in a circular pattern, having no definite poles. But if the wire is coiled like thread on a spool, the magnetic field around each coil amplifies that of its neighbor, resulting in one large magnetic field. The more numerous the loops or coils of wire, the stronger the magnet produced. This magnet can be turned on and off simply by turning on and off the electricity flowing through it. If there is no electrical current, there is no magnetic field. This type of magnet is called an electromagnet.

A simple example of an electromagnet in action is the common doorbell. When you push the button, electricity flows through an electromagnet, attracting a hinged piece of metal to it. In its movement toward the electromagnet, the metal strikes a chime. When you release the button, the electromagnet releases the metal, and as it springs back to its original position, it strikes another chime, resulting in the familiar “ding-dong.” In this, and sometimes in more complex ways, magnets and electromagnets are at the heart of most electrical appliances.

Electric motors are based on the electromagnet. To state it simply, electromagnets arranged in a circle are turned on and off at precisely timed intervals, and the attractive/​repulsive properties of the magnets set an armature spinning within the circle. Thus electric motors of varying strengths do many chores for us, from turning the hands on our clocks to speeding heavy commuter trains to their destinations.

Switches, relays, solenoids, meters, gauges, and so many other instruments of the electrical industry are based on this simple relationship between electricity and magnetism. Why, magnetism permits the sound of your voice to be transmitted over telephone wires to your loved ones, and then allows you to hear their voices in reply! Electromagnets within the speakers of your radio, television or stereo set convert electrical impulses into sound, reproducing the original with amazing fidelity. Yes, magnetism allows you to make a tape recording of your son’s first words, or your daughter’s first violin solo, and to relive those precious moments years later.

It is a beam of electrons focused precisely by magnetic fields that produces the picture on your television set. This same focusing of electron beams by magnetism allows scientists to peer into the world of the infinitesimally small by means of electron microscopes.

Electricity’s relationship to magnetism works in a converse way as well. The generators that produce electricity depend on magnetism. Powerful permanent magnets are arranged in a circle, and turbines driven by steam or water cause coils of wire to rotate through these powerful magnetic fields. This movement of the wire causes an electrical current to flow in the wire. Then this current is transformed to a suitable voltage and passed on to our homes.

It would not be an overstatement to say that the entire electrical industry would not exist today if it were not for that powerful servant of man that we call magnetism.

[Pictures on page 20]

The magnetic field around a wire with electricity flowing in it is shaped like a doughnut and has no definite poles

When the wire is coiled, electrical current within it will produce an electromagnet with definite magnetic poles