How do I make an electromagnet with a battery?

While almost any battery will work, try a single D cell. In addition, you will need

• a D-cell holder, Radio Shack part number 270-403
• magnet wire (wire with especially thin insulation, designed for winding), Radio Shack part number 278-1345
• A steel bolt, we will wind the coil on the bolt. For example a 1/2 in diameter by 2 inch long bolt will work well, available at any hardware store
• a small piece of sandpaper or emery paper
• (optional) soldering iron or soldering gun and a bit of solder
• (optional) a compass

The Radio Shack magnet wire kit (278-1345) has 200 feet of 30 gauge wire. Wind the entire 200 feet around the diameter of the bolt, making as many turns as you can, give yourself at least 6 inches of wire at both ends of the coil.

Using the sandpaper or emery paper, carefully scrap off the insulation at the end of each wire. The wire will appear bright and shiny when the insulation is removed. If you have a soldering iron, apply a little solder to the ends to make a better contact. Connect the ends to the battery holder and insert the battery. While current flows through the coil, the bolt becomes an electromagnet, capable of picking up small pieces of any ferromagnetic material, paper clips or nails, for example. The strongest magnetic forces should appear at the ends of the bolt, or poles, labeled "N" and "S" in the sketch below. Place the compass at either end of the bolt. The needle should turn when you energize the coil and return to its normal orientation when you remove the battery.

Turn off the electromagnet by removing the battery from the holder. Do not leave the battery connected too long, it will run down the battery and possibly damage the coil. Disconnect the battery immediately should either the coil, battery or bolt become hot to the touch!

Good luck!

Disclaimer: While the information contained here is believed to be accurate and reliable, the user assumes all responsibility. If you don't know what you are doing, by all means get help!

Too complicated? Would you rather just buy an electromagnet like the one described above? We can send you the electromagnet shown above for $15.00, plus shipping, battery not included.