Observing How the Motor Operates

D. Observing How the Motor Operates

 1. Observe what happens when the armature spins.

  • The armature spins in one direction only.
  • Reversing the battery reverses the direction of spin.
 2. Explore how the position of the magnet affects the operation of the motor.

  • Flipping over the magnet reverses the direction of spin.
  • Bringing the magnet closer to the armature increases the rate of spin.
  • Holding the magnet above the armature stops the spinning, and the armature may jump up and stick to the magnet—     the armature spins much better with the magnets held slightly below, rather than above.

E. Changing the Motor Speed and Load
 1. With the armature spinning, carefully bring the magnet closer to the spinning armature, and then further away. What      do you observe? (Look at everything in the circuit.)

    As the magnet is brought closer, the armature spins faster, and the bulb dims.
 2. So far, the spinning armature has been unloaded--it has not been doing any work, except against its internal friction.      As the armature turns, gently squeeze the armature shaft. What do you observe?

     When the shaft is squeezed, the armature spins more slowly and the bulb brightens.