How to Make a Simple Electromagnet Use Less Power

Choose a better core. The basic electromagnet is a series of coils of wire, which is connected to a power source. If you put an iron rod in the coil -- or wrap the coil around an iron core -- the electromagnet is a lot stronger. The stronger the electromagnet is the less power you have to use to get the same magnetic strength. There are even cores, other than iron, that produce an even stronger magnet, which means you can use even less power to get the same magnetic force. Unfortunately, these new synthetic materials are more expensive than iron.

Wind more loops of wire. The more loops there are, the stronger the magnetic field and the less power you need to get the same magnetic strength. Increasing the loops makes the wire longer, which means that it has more resistance and therefore uses more power. If you are going to increase the loops, it is important that you use a low-resistance wire. This means using a wire made out of a material that has low resistance. Unfortunately, some of the very low-resistance materials that can be made into wire -- like gold -- are more expensive than the more traditional materials, such as copper. Increasing the diameter of the wire also lowers the resistance.

Decrease the diameter of combined wire and insulation. Electromagnets are often made with enameled copper wire because the enamel insulation makes the combined diameter of wire and insulation as small as possible. When there are lots of loops, the wire must be wound in layers. After a few layers, the wire is so far away from the core that its magnetic field has little effect on the strength of the magnet. Loops, length of wire and conductivity of the material the wire is made of all work together to produce an optimum electrical power versus magnetic strength. Find this optimum to get the magnetic strength you need while using a minimum of electrical power.