How Motors Work

By Stu Grove on May 22, 2015

For this year's Science Fair Introductory Physics student Kevin chose to conduct a research-based project exploring the topic of electric motors. This project found Kevin identifying and defining the role of each of the components that combine to form a fully functioning D/C motor, of the variety that one might find in a drill, battery-powered fan, or other device. Kevin chose to link his project to the physics topics of energy and electricity by testing the functionality of a motor (control) using batteries of varying voltages (variable). As part of his presentation Kevin mounted a motor he extracted from an old drill onto a base, along with three different battery sources. Visitors were delighted as Kevin demonstrated how the speed of the motor was greatly effected by the voltage of the battery used. Additionally, Kevin placed the various components of a small toy motor he had dissected on display whilst describing to his visitors how each part was essential to the functioning of the motor overall.       

 

Student shows off motor display

Scientific Question:

What force and energy does a motor use to make an object move?

Hypothesis:

If you are making a motor, you have to understand magnets and electromagnetic fields, because an electric motor involves a lot of that. Also, with different types of batteries, the motor may turn at different speeds because different batteries let different amounts of power through and the speed depends on how much power is going through the motor.

Experiment Details:

This experiment is basically about how electric motors work. It's about the kind of force and energy an electric motor produces. The speed of a motor depends on how much power is going to it. So if you have an electric motor running on a battery, the speed of the motor will depend on the kind of battery that's powering it. The higher voltage of electricity you have, the faster the motor will turn. Also, if you flip the battery around so the positive and negative sides are opposite each other, the energy will move the other direction, which will make the motor turn the other direction.
 

Key Points:

student with full poster and motor demo

Direct current (DC) is the unidirectional flow of electric charge. A source of direct current is a battery and this will be what I'll use in my experiment. Electromagnets are used in electric motors. An electromagnet is a coiled wire wrapped around a metal rod. The stationary magnets partially surround the coiled wire for the electromagnet. The attraction and repulsion of the magnets cause the armature to rotate when an electric current is applied. The commutator is two or three curved flat medal disks attached to the armature. They touch the brushes to complete the electric circuit. They also flip the magnetic field so the motor turns more efficiently. The brushes touch the commutator which allows continuation of the electric current. The power supply in this experiment is going to consist of batteries. You can get power from batteries, solar power, or plugging into a wall outlet.

Conclusion:

It is true that you have to understand magnets and electromagnetic fields because a motor has a permanent magnet which partially wraps around a coil of wire which then becomes an electromagnet when electricity from the battery is going through it. When I hooked up different batteries to the drill motor and the fans, they went different speeds with different batteries.  When I flipped the batteries around between the two wires, the motor moved the other direction because the current was going the other direction.
 
demonstrating materials
 

Materials

  • Battery types: 9v, 3 AA, 1 AA
  • Electric motor taken from a drill
  • Small toy motor parts
  • Wire
  • Alligator Clips
  • Wooden Base
 
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