Lesson 1/Learning Event 1
FIGURE 9. LINES OF FORCE IN A COIL.
An electromagnet is made stronger by increasing the amount of current flowing in the conductor or
weaker by decreasing the current. It can be concentrated to make the magnetic field stronger in
one area by winding the conductor into a coil. The more turns in the coil, the stronger the
magnetic field in that area. Often, an iron core is placed inside the coil to make the magnetic field
even stronger. This is possible because the lines of force travel through iron easier than they do
through air.
The repelling and attracting forces of magnetic fields of electromagnets are used in electric motors
and other devices to do mechanical jobs. In automotive vehicles, these jobs range from cranking
the engine to opening or closing small contact points in a relay switch.
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