Creating an electromagnet using a battery, nail and wire is an excellent demonstration for elementary school age children. This task does require some adult supervision as there is electricity involved. It provides an opportunity to see how electrical current flowing through a coil creates an electromagnetic field, which is transferred to the nail. Whenever there is current flow, there is also heat generated by the resistance of the wire. If there is more current flowing, then more heat will be generated. If there is too much current, the heat could melt the wire and cause a burn injury.
A higher voltage battery will cause a stronger electromagnet. More wraps of wire on the nail will also cause a stronger electromagnet. You can experiment with a battery of less voltage, for example a C cell or an AA battery, to see the difference.
A higher voltage battery will cause more current flow, which will generate more heat. This could cause the wire to melt if there is enough current. Do not use a car battery or any large battery as this could cause immediate melting of the wire and its insulation, which could result in serious injury. Limit this demonstration to a D cell battery or smaller.
Strip about 1/4 inch of the insulation from each end of the wire. Single stranded wire works the best if available. It is easier to keep wrapped around the nail.
Wrap the wire around the nail tightly. Leave about 1/2 inch of the nail tip exposed. You can also wrap electrical tape around the wrapped wire to keep it from coming undone.
Attach one end of the stripped wire to the bottom, or negative (-) end, of the battery with a piece of the electrical tape.
Touch the other end of the stripped wire to the top or positive end (+) of the battery. When both ends of the wire are touching the battery, the nail is an electromagnet. It is not recommended to attach the second end of the wire to the battery with electrical tape. The two ends of the wire should only be touching the battery for a short time.
Pick up the paper clip with the nail tip. Leaving the wire touching the battery at both ends causes three things to happen: The nail becomes magnetized, the wire becomes warm and the battery loses power. Eventually the battery will become depleted. This is not easy to recognize because the longer the battery remains connected, the more magnetized the nail becomes. If you try using a new nail with the same battery, you will see that the new electromagnetic nail is not as strong as the old one.
- D Cell Battery image by ike from Fotolia.com