ELECTRIC MOTOR

Abstract
Did you know that you probably used an electric motor today? Yes, that's right. If you put on clothes that were washed in a washing machine, rode in a car, ate food from a fridge, warmed up lunch in a microwave, or played a video game, you used an electric motor! Try this science fair project and you'll learn how to make a simple electric motor by having two magnets "talk" to each other. As they interact, they will alternate between "liking" each other (being pulled together), and "disliking" each other (pushing away from one another). All that pushing and pulling will create some serious spinning, and you will have built an electric motor! Objective
To learn how to build a simple electric motor and to determine which motor design produces the fastest rate of spin.
Introduction
So, what do windshield wipers, CD players, VCR's, blenders, ice makers, computers, and talking toys have in common? They all contain electric motors! In fact, if you walk through your house, it is possible to find as many as 50 electric motors hidden in electrical devices, appliances, and toys in every room in your home. They are a very important and vital part of modern life.
Have you ever played with magnets before? If so, you are well on your way to understanding how simple electric motors work. Magnets have a magnetic field with a north pole and a south pole. If you play with two magnets and try to push the north poles of each magnet together, the magnets will not go together. They will repel each other. The same thing happens if you try to push two south poles together. If two poles are the same, they will repel each other. If, however, you play with two magnets and bring the north pole of one close to the south pole of another, they will attract each other and stick strongly together—opposites attract!
An electric motor uses the attraction and repelling properties of magnets to create motion. An electric motor contains two magnets: a permanent magnet (also called a fixed or static magnet) and a temporary magnet. The temporary magnet is a special magnet, called an electromagnet. It is created by passing an electric current through a wire. The permanent magnet has a magnetic field (a north pole and a south pole) all the time, but the electromagnet only has a magnetic field when current is flowing through the wire. The strength of the electromagnet's magnetic field can be increased by increasing the current through the wire, or by forming the wire into multiple loops.
To make an electric motor, the electromagnet (the temporary magnet) is placed on an axle so it can spin freely. It is then placed inside the magnetic field of a permanent magnet. This is when things get interesting! When a current is passed through the electromagnet, the resulting temporary magnetic field interacts with the permanent magnetic field and attractive and repelling forces are created. These forces push the electromagnet (the loops of wire), which is free to spin on its axle, and an electric motor is born.
Which direction the loops of wire are pushed in can be predicted by Fleming's Left Hand Rule for Motors. Hold your left hand out, as shown in Figure 1.

Figure 1. This drawing shows Fleming's left hand rule for motors. (ExplainThatStuff.com, 2008.)

Your pointer finger represents the direction of the field (from north to south) of the permanent magnet. Your middle finger represents the direction of the electric current (which flows from the positive terminal of the battery to the negative terminal of the battery). The direction of the force on the loop of wire (the electromagnet) is predicted by the direction of your thumb. The thumb, therefore, tells you which direction the electromagnet will spin. Try Fleming's Left Hand Rule on the example in Figure 2 and see if your thumb predicts the direction in which the electromagnet will rotate.

Figure 2. This animation shows the direction the loop of wire (the electromagnet) will rotate, based on Fleming's Left Hand Rule for Motors. (ExplainThatStuff.com, 2008.)

Terms, Concepts, and Questions to Start Background Research

• Electric motor
• Magnet
• Magnetic field
• Repel
• Attract
• Permanent
• Static
• Temporary
• Electromagnet
• Axle
• Fleming's Left Hand Rule for Motors
• Insulate
• Beakman motor

Questions

• Where can you find electric motors? How many can you count in your home?
• What happens when two magnets get close together?
• What is the difference between a permanent magnet and a temporary magnet?
• How do you make a temporary magnet (an electromagnet)?
• How can you increase the strength of an electromagnet?
• What are the parts of a simple electric motor? Which of those parts can spin?
• What causes the spinning an electric motor?
• What does Fleming's Left Hand Rule for Motors tell you?