Where does electrical power come from? Everyday life experiences generally do not involve thinking about what the wall outlet is connected to. You expect to be able to plug an electrical device in and off you go. It may only be during a power outage that we thinking about electrical service to a home or business or school and how it gets there. A power outage raises short-term interest in where the failure occurred and why. The actual “usefulness” of knowledge about power generation is somewhat limited by the reliability of the US power supply. Most of us don’t need back up power generators.
Electric current is made by moving a coil of wire through a magnetic field. Watch the video on power generation on this website to see how power is generated for homes, business, and communities.
But there are ideas in science that have usefulness related to power generation and everyday life. In this activity you build a simple electric motor. The wire loop spins in its holder because electrical current running through loops of wires creates a magnetic field. The wire is insulated but the ends have been stripped bare. The best wire is wire that has an insulating lacquer for use in motor windings. This wire is thin and light. The magnets below the loop are attracting and repelling the loop of wire. That causes the loop to spin. See the diagram to see what you need to build this motor: (http://theselsproject.org/wp-content/uploads/2013/03/high-performance-shoe-string-motor-copy.pdf)
One of the videos for this activity (https://vimeo.com/63021015) shows a loop that did not work well. The wire seems to be too heavy. The other video (https://vimeo.com/63021028) shows a loop made from wire that is insulated with lacquer. This wire is used in motor windings. The ends of the wire have had the lacquer sanded off making a good electrical connection to the battery.
Electric current creates a magnetic field
Moving a coil of wire in a magnetic field creates an electric current
Next Generation Scientific Standards
Scientific and Engineering Practices:
– Planning and carrying out investigations
– Energy and matter: Flows, cycles and conservation
- What determines how fast the wire loop spins around? Think about the parts of the simple motor that can be varied and investigated. There are three main parts: wire loop, battery, and magnet. All three have larger and smaller versions that can be used. Note that the wire can vary with gauge, how thick or thin the wire is. The number of loops can also be varied.
- In getting the wire loop to spin, sometimes it seems to get attracted to the magnet as if it were a magnet itself. Why is that? One thing to think about in this case is that when the loop is spinning, the bare ends sitting inside the safety pin loops are bouncing around. This leads to a third question.
- Why do the bare ends of the loop bounce around when the loop is spinning? Note that this means that the ends are sometimes connected to the battery and sometimes not.