How to Make a Magnet With a Bolt & a Battery

Electromagnets were used to send Morse code.

Electromagnets use the flow of an electrical current to align the atoms of ferrous metals, creating a magnetic field. The magnetic field forms when the electricity travels around the metal through a small diameter continuous wire and the magnetic field dissipates when you stop the flow of electricity from revolving around the metal. How you apply the wire to the metal and the type of metal used to build the electromagnet will affect the strength of the electromagnet's magnetic field.

Things You'll Need

• 3/8-inch nut
• 3/8-inch bolt, 3 inches long
• Tape measure
• Pair of scissors
• Paper
• Electrical tape
• 24 to 36 inches of coated magnet wire
• 220-grit emery cloth
• Rubber band
• D-cell battery

Instructions

1. Thread the nut onto the bolt and spin the nut clockwise until 1/4 inch of the bolt extends beyond the nut.

2. Measure the distance between the inside edge of the nut and the flat interior edge of the bolt head with the tape measure.

3. Cut the paper to the length you measured in the previous step with a pair of scissors, wrap the paper around the threads of the bolt and hold the paper in place with a piece of electrical tape.

4. Wrap the magnet wire around the bolt. Make a U in the wire, with one leg of the U roughly 6 inches long, and place the U over the shaft of the bolt. Slide the wire tightly to the head of the bolt and evenly wrap the wire around the paper-covered shaft of the bolt in a clockwise direction. When you reach the nut on the end of the bolt, make a second layer of wire by evenly wrapping back toward the head of the bolt.

   Stop wrapping the wire when you have roughly 6 inches of wire hanging in front of the nut threaded in the end of the bolt.

5. Place electrical tape around the wrapped wire to hold its ends in place.

6. Rub the first 1/2 inch of each hanging end of wire with the emery cloth to remove the protective coating from the wire. The wire will shine when you have the coating removed.

7. Place the rubber band around the D-cell battery, set one cleaned end of wire against each end of the battery and pull the rubber band over the wire ends to hold the wires against the battery to complete your electromagnet.

Tips & Warnings

• Keep a spare battery close, as an electromagnet will drain a battery fast.

• Immediately remove the wires from the battery if you notice the battery or magnet wire getting hot, as this could lead to the battery exploding and possibly causing severe burns.

References

• DeltaSee.org: Build It: Electromagnet
• Bizarre Stuff: Fun with electromagnets
• Lawrence Berkley National Laboratory: Moving Electrons