Wrap thin, uninsulated metallic wire, preferably copper, around an iron or steel rod or nail. Tape the wire down to the rod or nail with electrician's tape, attach the wire connected to what will be the negative end of the rod to the negative end of a one and a half volt battery, and the wire connected to what will be the positive end of the rod to a knife switch. Connect the wire coming from the other end of the knife switch to the positive end of the battery. When the circuit is closed -- that is, when the knife switch is thrown into the 'on' position -- current will run through the wire and pass through the rod, transforming the rod into an electromagnet. Modify this simple electromagnet by altering the size and thickness of the wire or the rod, or the power of the battery.
Electromagnets possess the same magnet properties as standard magnets. Unlike standard magnets, however, their magnetism relies directly upon the electricity pulsing through the iron or steel rod. Consequently, students can experiment with the strength of an electromagnet by first testing the rod's magnetism on objects when the knife switch is not thrown. Then, students test the rod's magnetism when the knife switch is throne. The rod should be able to pick up small metallic objects such as paper clips and thumbtacks. Students can then increase the number of batteries or the individual battery's power to see if an increase in electric power results in an increase in magnetic power.
In 1820, Hans Orsted first discovered the magnetic properties of a metal rod through which an electrical current ran. He made this discovery not by witnessing the rod's magnetic power, but by identifying the electromagnet's magnetic field. Unlike with standard magnets, students can use electromagnets rather easily to create a visual depiction of the magnet's magnetic field. Place iron filings on a sheet of white paper, and put the non-electrified electromagnet directly underneath those filings on the other side of the paper. Throw the knife switch to turn the electromagnet on. The electromagnetic field of the electromagnet will rearrange the filings to a shape that seems to outline the rod, but which has concentric circles radiating out from the poles of the electromagnet.
Many scientific and common devices use electromagnetic devices in order to function properly. Students can build various devices such as a small transformer or spark generator, a Jacob's ladder or controlled, climbing spark generator and even audio speakers. Upon creating their own electromagnets, students use easy-to-follow how-to guides to create these common devices so as to further examine the many uses of electromagnets.