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Application of Magnetic Induction

LEARNING COMPETENCY

Perform demonstrations involving magnetic induction in contexts such as, but not limited to, power generation, transformers, radio tuning, magnet falling in a copper pie, and jumping rings.

APPARATUS

  • Electromagnet (to be made from small permanent magnet spool of 28-gauge magnet wire, large bolt, nail, or steel rod, electrical tape)

  • Permanent magnet

  • Multimeter

HOW TO CREATE AN ELECTROMAGNET

Wrap a single layer of electrical tape around the steel bar (or bolt, or mail) to protect the wire from abrasion. Proceed to wrap several hundred turns of wire around the steel bar, making the coil as even as possible. It is okay to overlap wire, and it is okay to wrap in the same style that a fishing reel wraps line around the spool. The only rule you must follow is that all turns must be wrapped around the bar in the same direction (no reversing from clockwise to counter-clockwise).

LET'S INVESTIGATE

EXPERIMENT ON ELECTROMAGNETIC INDUCTION

Learning Objective: To establish the relationship between magnetic field strength and induced voltage

Schematic diagram of the set-up. Photo credit to http://www.allaboutcircuits.com/

Electromagnet. Photo credit to http://www.allaboutcircuits.com/

Illustration of the set-up. Photo credit to www.nationalstemcentre.org.uk

PROCEDURE

Electromagnetic induction is the complementary phenomenon to electromagnetism. Instead of producing a magnetic field from electricity, we produce electricity from a magnetic field on this experiment. There is one important difference, though: whereas electromagnetism produces a steady magnetic field from a steady electric current, electromagnetic induction requires motion between the magnet and the coil to produce a voltage.

Connect the multimeter to the coil, and set it to the most sensitive DC voltage range available (refer to the illustration above). Move the magnet slowly to and from one end of the electromagnet, noting the polarity and magnitude of the induced voltage. Experiment with moving the magnet, and let the learners discover what factor(s) determine the amount of voltage induced. Try the other end of the coil and compare results. Try the other end of the permanent magnet and compare.

If using an analog multimeter, be sure to use long jumper wires and locate the meter far away from the coil, as the magnetic field from the permanent magnet may affect the meter’s operation and produce false readings. Digital meters are unaffected by magnetic fields.

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