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The National MagLab is funded by the National Science Foundation and the State of Florida.

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Inductive Pendulum

Get the swing of electromagnetic induction with this device.

Electromagnetic induction is the principle that a voltage can be induced in a wire or other conductor that is moving in an external magnetic field; if the conductor is part of a circuit, a current will flow. That’s the case in the inductive pendulum seen here.

Instructions

  1. Check out the setup. The pendulum has a small lamp on one end, and a copper coil at the other.
  2. Note the horseshoe magnet placed so that the copper coil is in between the poles of the magnet.
  3. Click the swing button and see how the light bulb glows.
  4. As the pendulum moves the copper coil in and out of the magnetic field, this induces a current in the coil, causing the lamp to light.
  5. Observe that the lamp goes out when the copper coil is not passing through the magnet.
  6. Notice also that the lamp grows dimmer as the pendulum slows and goes out completely as it stops. The slower the pendulum, the less dramatically the magnetic field changes, resulting in less and less current generated.