How to Make a Varying Electromagnet Field
Magnetism is a force generated by certain materials, called magnets. It interacts with other magnets and with many metals. It can cause these things to be drawn closer to the magnet or pushed further away from it. This magnetic force is generated by the motions of tiny electrical currents deep inside the magnets, according to Kristen Coyne of the National High Magnetic Field Laboratory.
Using natural magnets is not the only way to generate a magnetic field. You can build a device called an electromagnet. Like natural magnets, electromagnets use the motion of electric currents to generate magnetic fields. When assembled correctly an electromagnet can be made to create a variable field, one capable of changing its strength.
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Things You'll Need
- Magnet wire, any gauge, at least 5 feet long
- Nail, spike or some other small piece of iron three or four inches in length
- D-cell battery
- Variable resistor
- Fine grit sandpaper
- Several inches of copper wire
- 2 wire connectors
- Wire stripper
- Electrical tape
Instructions
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1
Wind the coil. Leaving six or more inches trailing off at the bottom, start wrapping the magnet wire around the iron object (called the “core”) from the bottom repeatedly to create a coil. There is no easy way to tell the best number of wraps to use because the math involved is complicated, but as a general rule of thumb, more is better. Leave several inches of wire hanging off the top of the coil as well.
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2
Sandpaper the ends of the magnet wire until the enamel is worn off. This is the only way the electromagnet will be able to conduct electricity.
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3
Strip the copper wire. Using the wire stripper, remove an inch or two of insulation from the ends of the copper wire.
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4
Using a wire connector, attach the variable resistor to one end of the coil of wire. Attach the other end of the resistor to one end of the copper wire with the other wire connector. Attach the other end of the copper wire to either terminal of the battery with the electrical tape. Attach the other terminal of the battery to the other end of the coil wire, also with electrical tape.
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5
Turn the knob of the variable resistor. By doing this you are changing the resistance of the circuit to current flow. This changes the amount of current flowing in the circuit. The electromagnetic field that the electromagnet generates will vary in strength along with the current.
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Tips & Warnings
Never touch exposed wires or any element of the circuit other than the insulated coil and the resistor knob.
