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Electromagnetic Induction

When a permanent magnet is moved inside of a copper wire coil, electrical current flows inside of the wire. This important physics phenomenon is called electromagnetic induction.

In 1831, the great experimentalist Michael Faraday set out to prove electricity could be generated from magnetism. He created numerous experiments, including the simple but illustrious setup of the copper wire and permanent magnet . Faraday wrapped the copper wire around a paper cylinder and attached the ends of the coil to a galvanometer, which is a device that detects and measures electrical current.

Instructions

  1. Click and drag the bar magnet back and forth inside the coil.
  2. Observe the galvanometer and see that there is only current detected when the magnet is in motion.
  3. Increase the speed of the magnet’s movement (by dragging the magnet faster) to see how this increases the current.
  4. Add turns to the wire and notice how the reading on the galvanometer increases.
  5. Flip the magnet. Watch how the direction of the field impacts the direction of the current (depicted with black arrows.)

When the permanent magnet moves inside of the coil, the mechanical energy of the movement is converted into electricity. While this experiment was uncomplicated, it was also revolutionary. Faraday’s work was translated into an equation by James Clerk Maxwell, who went on the expand on Faraday’s findings and create other equations that are the backbone of the study of electromagnetism. Electromagnetic induction is still crucial to the modern world, and is used in devices like generators, transformers, and electric motors. It can also be used to wirelessly charge devices like an electric toothbrush or phone.

To give credit where credit is due, Joseph Henry was not far behind in his independent discovery of electromagnetic induction in 1832. Dig deeper into the history of important scientists in our Pioneers section.