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DIY: Turn a Bolt into an Electromagnet

DIY: Turn a Bolt into an Electromagnet

Unlike the magnets on your fridge, electromagnets have a magnetic field that runs on electricity. When you break the circuit, just like turning off a light switch, the magnetic properties disappear.

They are used in all kinds of electronic devices, like headphones, loudspeakers and computer hard drives. They are also used in magnetic resonance imaging (MRI) machines, which help healthcare workers see what’s going on inside your body.

The magnet in an MRI machine is so powerful, the people who go near it have to be very careful about any metal they might be wearing—it can pull the glasses right off your head!

Building Your Own Electromagnet

The video above showed one way to turn a fastening bolt into an electromagnet. Here is an even easier way to do it.

You'll need:

  • a bolt and 1 nut for the other end
  • a spool of magnet wire (copper wire with a special enamel insulation around it)
  • one AA battery
  • some paper clips or other small magnetic objects
  • sandpaper or a nail file
  1. Measure out and cut five feet of magnet wire.
  2. Use the sandpaper or nail file to remove about two inches of the enamel (red) insulation covering the wire from each end of the wire.
  3. Place the nut on the other end of the bolt.
  4. With about four inches extending past one end of the bolt, wind the entire length of wire around the bolt, leaving four inches loose at the same end.
  5. Curl a small bit of the uninsulated copper at each end of your wire for your battery “holder.”
  6. Use your index finger and thumb to connect the ends of the wire to the positive (+) and negative (-) ends of the AA battery.

Now you’ve made an electromagnet! Experiment with different items to see what it will pick up: paper clips, thumbtacks, bottle caps and more.

Please note: As always when dealing with electricity, it’s important to BE CAREFUL! Use your magnet for only short periods of time, because the ends of the battery can become very hot. And be sure to disconnect your electromagnet when you are done so it doesn’t completely drain your battery.

Some History on Electromagnets

Originally, electricity and magnetism were thought of as two separate forces. But in 1820, a Danish scientist named Hans Christian Ørsted made a surprising observation. While setting up his materials to give a lecture, he noticed a compass needle moved away from magnetic north when the electric current from the battery he was using was switched on and off.

This convinced him that magnetic fields radiate from all sides of a wire, carrying an electric current just as light and heat do. He believed it confirmed a direct relationship between electricity and magnetism.

In 1873, a Scottish scientist named James Clerk Maxwell published A Treatise on Electricity and Magnetism, in which the interactions of positive and negative charges were shown to be caused by one force.

The resulting branch of physics, electromagnetism, involves the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles. The electromagnetic force is one of the four fundamental interactions (commonly called forces) in nature.

For more information and activities on electromagnetism, check out these links:

Jefferson Labs "How to Make an Electromagnet”

Science Net "Build an Electromagnet"