Lesson 1/Learning Event 1
By now you may be thinking, so what does magnetic force have to do with electricity? Well, let's
give this matter more consideration and find out what the connection is and how it may be used.
FIGURE 8. ELECTROMAGNETISM.
First, think about this experiment that is easily done. Pass a wire through a hole in the center of a
piece of cardboard. With the cardboard level, sprinkle iron filings on it around the wire. Now
connect the wire to a battery so it conducts current and tap gently on the cardboard. The filings
will then form circles around the wire. This proves that a magnetic field circles the wire. A
magnetic field created by electricity, such as in this experiment, is known as
We can carry the experiment out farther and prove that the lines of force about the wire have
direction and that the direction is affected by the direction of current flow. Start by placing a
compass at various points in the magnetic field around the wire. You will notice that the compass
needle always aligns with the lines of force, with the north pole of the needle pointing in the
direction of the magnetic field. Now reverse the wires on the battery terminals so the current flows
in the opposite direction. The north pole of the compass needle will also reverse direction, proving
that reversing the direction of current in the wire reverses the direction of the magnetic field.