PASCO SE-8657 MOTOR ACCESSORY - Manual (Page 16)

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Motor Accessory 012-06247A
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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 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 2 according to whether it is the north or south
pole of the electromagnet.
c) Determine the polarity of the Variable Gap Magnet in the same way. Label its poles “N”
and “S” in Figure 2.
➂
Predict the direction the armature will rotate when you release it from the position of Figure
2.
Will the motor rotate clockwise or counter-clockwise?
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.
➤ If the motor does not start in either direction, turn off the power and ask your
teacher for help.
➃
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 counter-clockwise?
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.
➄
While the motor is running, raise the voltage to approximately 8 volts.
a) What happens to the motor’s rotational speed when you raise the voltage?
b) Is the relationship of the motor’s rotational speed and voltage of the DC current depen-
dent or independent?