User's Manual

11
012-07210A Permanent Magnet Motor
Procedure—Part B
1. Turn on the power. Adjust the output voltage to 6 volts.
2. Use the small cylindrical ceramic magnet to check your predictions from steps 5 and 6 above.
The painted face of the magnet is its North Pole (north-seeking pole). [You can verify this by
hanging the magnet from a thread and observing that the painted face points toward the North
(toward the earth’s north magnetic pole, located in northern Canada).] With the armature and
power supply leads oriented as in Figure 1.2 and the power turned on, hold the ceramic magnet
near the ends of the armature. If both poles of the ceramic magnet attract the armature, the pole
with the stronger attraction will be the opposite pole.
a) Does the result of this test agree with your predictions in steps 5 and 6?
b) Label each end of the armature in Figure 1.2 according to whether it is the north or south
pole of the electromagnet.
c) Determine the polarity of the Permanent Magnet Motor in the same way. Label its poles
“N” and “S” in Figure 1.4.
3. Predict the direction the armature will rotate when you release it from the position of Figure 1.4.
Will the motor rotate clockwise or counterclockwise?
If the motor does not start up immediately, try turning it by hand in the predicted direction. If
that fails, try turning it in the opposite direction.
4. Turn off the power and reverse the positive and negative leads to the motor. Before turning the
power on, predict the direction of rotation.
a) Will the motor rotate clockwise or counterclockwise?
Turn the power back on and immediately try spinning the motor to start it. If it doesn’t start, try
spinning it in the other direction.
b) Explain why the armature turns when you turn on the power.
➤If the motor does not start in either direction, turn off the power and ask your
teacher for help.