5G20.60 Magnetization by Current

Concepts

Ferromagnetism, remanent magnetization

Overview

An electromagnet can be used to attempt to magnetize a few different cores, including a steel core, a soft iron one, and an aluminum one. Different objects can be picked up by the magnetizable cores, including coins and a nail. A small remanent magnetization occurs in the steel rod, allowing it to hold up a nail even after the electromagnet is no longer active. The remanent field is no longer able to hold up the nail once the rod and nail are separated.

Details

Equipment

  • [1] Electromagnet
  • [1] SPST switch
  • [1] Lantern battery
  • [1] Banana cable
  • [2] Alligator clip
  • [1] Lab stand
  • [1] 90-degree clamp
  • [1] 3-finger clamp
  • [1] Steel rod
  • [1] Soft iron rod
  • [1] Soft iron L-rod
  • [1] Aluminum rod
  • [3] Coins
  • [1] Permanent magnet

Classroom Assembly

  1. Mount electromagnet on lab stand.
  2. Hook up switch to battery and electrogmagnet.
  3. Make sure switch is open.

Important Notes

  • Make sure to open the switch when done!

Script

  1. Put a metal core inside the electromagnet.
  2. Close the switch.
  3. Check if the core is attracted to various items.
  4. Repeat for different cores.
  5. Open the switch when done.

 

Additional Resources

References

  • PIRA 5G20.60, 5G20.75
  • The Royal Canadian Mint documents the historical metal composition of circulated coins.
    Canadian coins made today are mostly cheaper nickel- or copper-plated steel, even the "nickel" 5-cent coin. The steel makes them ferromagnetic. Silver coins were common before 1968, when silver was phased out. Nickel became the predominant material from 1968 to 2012.
    Pennies were copper until 1996, when the Mint changed to copper-plated zinc. Modern copper-plated steel pennies first came out in 2000.

Disclaimer

  • Don't attempt this at home!

Last revised

  • 2020

Technicals

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If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.