Electromagnets: The Art of Magnetizing a Nail
The movement of electric charges through iron, copper, and some other metallic materials creates a magnetic field. When coils of metal wire are wrapped around an iron core, the magnetic field of the coils magnetizes the iron. Any current-carrying wire wrapped around an iron core is called an electromagnet. In this activity you will find out how the number of wire coils around the core of an electromagnet affects its strength.
D cell battery; Large iron nail; Insulated copper wire with about two inches of insulation removed from the ends (prepared by the teacher); Masking tape; Fifty small paper clips
- Wrap the copper wire around the center portion of the nail ten times. Leave each end of the wire free to attach to the battery.
- Use tape to connect one end of the wire to the positive battery terminal and the other end of the wire to the negative battery terminal. Caution: Over time the battery, wire, and nail can become hot, so be careful.
- Use the nail to pick up as many paper clips as possible.
- Disconnect the wire from the battery. Wrap the copper wire around the nail twenty times. Repeat steps 2 and 3.
- How many paper clips could you pick up with ten loops of wire around the nail?
- How many paper clips could you pick up with twenty loops around the nail?
- How does the number of loops of wire affect the magnetic strength of the iron nail?
- Answers will vary.
- Answers will vary, but students should be able to pick up more paper clips this time than the first time.
- As the number of loops increase, the strength of the magnet also increases.
Repeat this activity, but this time tape two D cell batteries end to end so the positive terminal of one touches the negative terminal of the other. Reconnect the wires to the free terminals. See how this affects the number of paper clips you can pick up.