It is called a homopolar motor because, unlike conventional DC motors, the polarity of the magnetic field emitted by the conductor and the permanent magnets does not change. A homopolar motor creates rotational movement because of what is known as the Lorentz force. This current then flows from the centre of the magnet to the edge where the wire connects, it travels up the wire back to the positive terminal of the battery and the circuit is complete.
But how does this generate movement you may well ask? Well, the key is the direction of the current and the magnetic field produced by the permanent magnet.
The direction of the magnetic field is demonstrated by the red arrows and the direction of current is shown by the blue arrows. Homopolar motors are amazing for demonstrating electromagnetic forces and explaining the concepts behind how motors work, but do not go expecting much from it.
Due to the high currents flowing through the wire the battery run out rather quickly. Additionally, the wire and battery can get extremely hot, so if you are planning to make one yourselves, be careful and handle with care! You can create your own simple motor with three common materials. Your email address will not be published. Let us know what you have to say:. Save my name, email, and website in this browser for the next time I comment.
Electric motors are devices that can transform electrical energy into mechanical energy by means of electromagnetic fields. There are some motors that can do the reverse, they can transform mechanical energy into electrical energy to operate as generators.
The two major part of an electrical motor is stator and rotor, the stator is the fixed part and the rotor is the mobile part.
Stator would act as a base that allows performing the rotation of the motor, and the rotation is not done mechanically it is done magnetically and the rotor is the rotating element that allows the transmission of mechanical energy. A homopolar motor is a direct current electric motor, which has two magnetic poles providing a static magnetic field. The homopolar electric generation process is done by using a moving electric conductor and this conductor will be enclosed by a unidirectional and constant magnetic field.
In this process, there is a strict relationship between the electric field, magnetic field, and inertia. The electric power which is generated is determined by their magnitude. If there is a flowing electric current then there will be a magnetic field too and reverse will happen too. Inertia is formed because of the moving mass in the surrounding space. The conductor will always cut unidirectional lines of magnetic flux by rotating the conductor around a fixed axis which is parallel to the magnetic field.
Many articles and books on this subject often begin with a historical perspective, recounting how some of the science behind electric motors was discovered. The science behind electric motors boils down to this: If you have an electric current flowing through a wire that happens to be in a magnetic field, it feels a force push on it.
Specifically, if you have a straight piece of wire sitting in a magnetic field as shown at right, the wire will feel a force pushing on it as shown, at right angles to both the wire and the magnetic field.
If you use the left-hand rule to help figure out the direction of the force, follow these conventions:. Homopolar motors were first invented by Faraday, and is perhaps the most simple type of electric motor. You just can't get much useful power out of it.
One thing it is good for is a great demonstration or subject of a science report. To demonstrate the homopolar motor in action, we will show motors in 3 different configurations.
We used two D82 magnets stuck together in the video below. A single D84 magnet would be the same, though we found it would work even with a single D82 magnet.
In this configuration, we hold the current-carrying wire still, along with the battery, and the magnet and screw spin. This is fairly easy to reproduce, though we had some problems with the screw slowly migrating off to the side. We solved this by adding a piece of tape with a hole in it. We have seen other videos where the battery was hit with a chisel or other sharp object to make a small indentation for the screw-point to sit in.
In this second setup, we hang the battery and magnet beneath a stationary steel bolt. The magnet-battery combination sticks to the bolt because a bit of the magnetic field goes up through the battery.
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