|FIELD: Physical Science||DURATION: 1.5 hr.|
|OBJECTIVE: Students will know the basics of how electric motors work.|
|METHOD: Students construct a simple electric motor using a battery and household items.|
|KEY VOCABULARY: Motor, magnetic field, current, electricity.||GROUP SIZE: Any|
Electric motors are found in a huge number of common appliances: fans, hairdryers, toy cars, weed whippers.
Electric motors all work on the same principle. This basic principle is that an wires carrying electrical current feel a force in a magnetic field. There are two key components to a motor: a permanent magnet and an electrical current. Permanent magnets are composed of particular materials, such as iron, which always emit a magnetic field around them because of small electrical currents always flowing inside. When a wire or coil of wires carrying a current is in this permanent magnet's field, it is pushed in a particular direction.
When a motor is plugged in, current flows in a coil of wire (we use a coil because the amount of force is proportional to the amount of current and a coil adds extra current with every loop). Because of the physical arrangement of the coil, the force it feels will start to spin it. As the coil comes around again to this original position in the magnetic field, it gets another 'kick' and spins again, and so on. When you get your coffee cup motor working, this will make perfect sense!
In this experiment you will arrange a coil of electric current-carrying wire and a permanent (bar) magnet to create a simple electrical motor.
MATERIALS (per group):