How to Make a Lifting Electromagnet
Electricity and magnetism are closely related and are in fact actually two aspects of the same phenomenon. Although much is still unknown about the nature of these forces, the basic concept is that an electric current produces a magnetic field. This field can be controlled through various means to produce electromagnets with specific operational power ranges and lifting strength. By wrapping several turns of copper wire around a magnetic material, such as iron, and controlling the electrical power through the conductor, a magnet of any strength can theoretically be produced, with sufficient ingenuity.
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Things You'll Need
- Copper wire, or magnet wire, insulated
- Steel nail or cylinder
- Variable voltage or current power supply
- Alligator clip jumper wires (optional)
Instructions
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Wrap several turns of the magnet wire around the steel shaft from top to bottom. When the end of the shaft is reached, continue winding in the same rotational direction, but back up to the top. Always continue winding in the same direction. When the top is reached again, continue back down. Continue to do this until the wire wrapping is of sufficient length. As more copper wire is used, the resistance will increase and thus require an increased voltage to run.
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Use Ohm's law to determine the coil's necessary power requirements. The current drawn by the coil is equal to the supply voltage divided by the coil resistance. Power usage is calculated as volts multiplied by amperes. The higher the gauge (smaller diameter) used for the wrapping wire, the higher the resistance through the coil will be. Increasing the resistance, by either increasing the wire's length or decreasing its diameter, for example, necessitates a higher voltage to draw an equal amount of current, and thus to maintain the same power.
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Secure the wire wrapping with tape or tie the end of the copper wire into a knot so it cannot unwind.
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Remove about an inch of enamel or insulation from each end of the wrapped wire. This electrically exposes the conductor and the wires serve as the terminals for the electromagnet.
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Attach the two ends, or terminals, of the electromagnet to a variable voltage or variable current power supply, either directly or using alligator clip jumper wires.
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Turn on the power supply and adjust voltage until the electromagnet is of desired strength.
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Tips & Warnings
Magnetic field strength is inversely proportional to the square of the distance between the two objects. If a paper clip can be lifted an inch away by a certain electromagnet, it would take another electromagnet nine times stronger to lift the same paper clip at a distance of three inches (3^2).
Keep in mind, magnetic fields are not properly explained by classical physics. Quantum physics and therefore advanced mathematics are needed to provide better prediction of what will happen under certain conditions.
For the engineer of lifting electromagnets, however, a trial and error approach can usually suffice to produce a strong enough electromagnet.
Generally, a stronger current produces a stronger magnetic field. If the wrapping of your copper wire is 10 ohms and you place 30 volts across it, 3 amperes will flow. 30 volts multiplied by 3 amperes is 90 watts.
The resistance of the copper wire wrapped around the steel shaft will create heat. Expect that the electromagnet will get hot and handle it appropriately, although this will not necessarily be the case. In the worst case, the enamel or insulation over the copper wire will burn and catch on fire. The copper itself may even become hot enough to melt. Consider placing a fuse in line with the electromagnet to protect the power supply in the event that this happens.
References
Resources
- Photo Credit medicina_nuclear-15 image by Paco Ayala from Fotolia.com
