19.2. The Electric Generator http://www.ck12.org
19.2 The Electric Generator
Objective
The student will:
- Understand how a generator produces an electric current.
Vocabulary
- alternating current:The induced current reverses direction at regular intervals. Electric generators produce
an alternating current. Generating alternating current is much more energy efficient (and therefore cheaper)
than using direct current. - electric generator:A device which converts mechanical energy into electrical energy.
Introduction
We learned earlier how a motor works. Recall that a rectangular loop of wire was placed between the opposite
magnetic poles so that the magnetic field lines passed through the loop. A voltage source (a battery, in our case)
provided an electric current through the rectangular loop of wire. The magnetic field exerted opposite forces on the
sides of the loop, creating a torque, and the loop turned.
What would happen if we disconnect the battery from the motor and turn the spindle of the motor by hand, as in
Figure19.7?
FIGURE 19.7
Turning a motor into a generator.In such a case, the magnetic flux through the loop would change, and an induced current would be produced in the
loop as shown inFigure19.8.
If the wires which were connected to the battery are now connected to, say, a small light bulb, the bulb would light
up – if we spin the loop fast enough. We have effectively turned a motor into agenerator! Your teacher may show