DIY Mini-Electromagnet

How to turn some simple items into a cool magnetic device

 The electromagnet seems to be one of the coolest inventions of the last two centuries. Electromagnets are main components of many electrical devices such as generators, motors, loudspeakers, relays, even MRI machines. They're virtually everywhere. Electromagnets have a magnetic field that is produced by an electric current and they usually consist of a large number of turns of wire which are wrapped around a core of material such as iron. As the current flows through the wire, the magnetic field is active. Their magnetic field then disappears when the current is turned off.

Electromagnets have been very useful in the scrap metal industry as well for moving large amounts of metal. I remember a time when I would walk around the docks with my father while watching heavy electromagnetic cranes picking up scrap metal by the thick metal plate that resembled a giant upside-down manhole cover, swinging it over to an open hatch on a ship, then letting the steel pile drop into the ship with a crash sounding something like a train wreck. It was great wandering around all that scrap looking for buried treasure in the form of small pieces of copper and brass that would get left behind, free from the clutches of that giant magnet. I could see why they used this method to move all this metal as there aren't many other ways to scoop up such a twisted mess of metal so efficiently.

The electromagnet was invented in 1824 by William Sturgeon, and was a horseshoe shaped piece of varnish coated iron, wrapped with bare copper wire. Although it only weighed seven ounces, it could lift 9 pounds. With technology and manufacturing of today, electromagnets are capable of lifting thousands of pounds. Obviously this mini version which I've assembled, is quite rudimentary and is shown only to lift a couple of metal clips, but it is still a cool little experiment to demonstrate the power of electromagnetism.

The Assembly

This mini electromagnet is made from a steel cotter pin, a short length of insulated solid gauge telephone wire, some electrical tape, and a AA battery. I begin by stripping the insulation from the two ends of the wire by about 1/2". Then, leaving a straight section of wire, I begin to wind the wire tightly around the cotter pin starting from the folded end of the pin, working my way to the opposite end of the pin. I make sure that each turn of the wire is tight against the next turn as well. Once the wire is near the end and is covering a good portion of the cotter pin, I extend both stripped ends of the wire out even with each other. Using the electrical tape, I secure one of the bare ends of the wire to the negative side terminal of the battery. Then I tape the other end of the wire to the side of the battery with the bare end extending up and just over the positive terminal of the battery. I bend this end of the wire so that it does not touch the terminal unless pressure is applied. Since the wire can get hot as the circuit is closed, I also use the tape to cover over this end of the wire to simulate a button and help insulate from the heat.

Once all the components are assembled, my small electromagnet is functional and ready to test. Using some small steel clips as my lifting material, I touch the wire to the positive terminal to energize the magnet and touch the end of the cotter pin to the clips. The magnetic force is strong enough to lift the clips from the table. However when the battery is disconnected, the charge is lost and the cotter pin loses its magnetism and can no longer lift the clips.

This is a neat experiment to try, given the simple materials involved and based on the short amount of time it takes to assemble. Some components can be substituted such as a nail in place of the cotter pin, and a heavier gauge wire with a larger capacity low voltage battery but caution and common sense should be taken with ANY experiments using ELECTRICITY! And children should ALWAYS seek adult supervision with these projects. It's EXTREMELY important to keep in mind that even low voltages can cause wiring to become HOT enough to burn skin if not properly managed.

I hope this little project encourages you to learn more about magnetism and its many uses in the world today. As always, keep putting those creative thoughts into action.