How an Electric Motor Works

What Devices Use Electric Motors?

When you use an electric razor, toothbrush, fan, or vacuum cleaner, you are using an electric motor. That’s probably no surprise, but how about this: washing machines, refrigerators, microwaves, your computer, and even your smartphone!

Confused? Don’t be. Something is needed to operate the refrigerator’s compressor. If there is a mechanical hard drive in your computer, then there is a small motor that turns the disk. And microwaves? Well, something must be spinning that glass plate around, right?

Even your electric cars (if you have one) have motors. They are used to spin the tires as you drive.

Bottom line is you probably go about your day using some device that uses an electric motor, so now that we know how our lifestyles are affected by these devices, let’s delve into how these motors work.

Overview

When an electric current runs through a wire, a magnetic field is produced and when there is a magnetic field, then metallic elements become attracted to it. And if we can maintain these elements to move towards the magnetic field and away from it at an ongoing, continuous rate, we can have a device that is constantly spinning. If we attach something to the part of the device that is constantly spinning, such as the glass plate in the microwave, we have harnessed the power of converting electrical energy into mechanical energy, or more specifically, we have created a motor.

How Does an Electric Motor Work?

First let us focus on the fact that there is a magnetic field that causes the components within the motor to constantly spin.

How is the magnetic field created? Our article on magnetic fields explains this, but in a nutshell, if we connect a wire to a battery, the electrons of each of the atoms will be move towards the positive pole of the battery. If we wrap the wire around a metal rod, the magnetic field intensifies.

Inside of an electric motor.
Inside of an electric motor. Photo: iStock

The Initial Stage

The motor is designed so that the the magnetic poles of a rod, called a rotor is always facing the same polarity of stationary magnet, called a stator, causing the rotor to spin around.

For example, when electricity is turned on, the polarity of one side of the rotor, let’s say the north side is initially facing the north side of stator, so there will be that repelling affect, causing the rotor to spin in the other direction.

The Next Stage

Well, that initial stage works just as it should because like poles repel each other, but that’s it. Then it stops, so in order for the rotor to keep spinning, there has to be a mechanism that will cause the poles to reverse continuously.

That is the job of the commutator. This entity keeps reversing the path of the electrons so that the poles are always repelling one another and consequently, keeps the rotor spinning.

Key Parts of an Electric Motor

Let’s review the parts of the motor:

    • Stator – The stationary part of the motor that creates the magnetic field that causes the rotor to spin. The stator is found in between two pieces of copper that conduct electricity.
    • Rotor – The rotating part of the motor that is placed within the magnetic field.
    • Shaft – The shaft of the motor connects the rotor to the stator and is used to power the equipment or machinery.
    • Commutator – The device that reverses the polarity each time the rotor spins. Like reversing a battery at every spin so that the electrons change course.
    • Fan – The fan is used to create air flow and increase the efficiency of a motor.

Final Words

Electric motors are a safe, efficient, and reliable way to power machinery and equipment. They are available in a range of sizes, voltages, and designs and can be powered by a wide range of energy sources, including fossil fuels and renewable energy sources like solar or wind. When you need to power equipment that needs to work independently from a source of manual power, an electric motor is a great choice.

 

Electromagnetism: From the Basics to Everyday Applications

Depiction of a wire wrapped around a nail with the wire connected to a battery creating a circuit and consequently creating an electromagnetic.
Depiction of a wire wrapped around a nail and connected to a battery, creating a complete circuit, resulting in the creation of an electromagnetic. When electrons start to run through the wire (from one end of the battery to the other), a magnetic field is produced and the nail is magnetized, consequently, the paper clips are attracted to the nail. If power shuts off, the paper clips will no longer have that attraction. Photo: iStock.

Let’s Start with a Piece of Metal

Let’s use iron for example. Touch it with another piece of iron and what happens? Nothing! Now take a bare wire, copper preferred. Wrap the copper wire around one of the pieces of iron and what happens? Still nothing!

Now grab both ends of the copper wire and connect it to a battery. What happens? Yep, still nothing – at least nothing noticeable that the naked eye can see! What is happening that we don’t see is that there is an electric current that is traveling through the wire.  As electrons are moving through the wire, a magnetic field is produced. 

When There is Electric Current, There is a Magnetic Field

Illustration of wires wrapped around metal and connected and disconnected to a battery
Left: Iron bar with wire wrapped around it (coil) and iron filings nearby laying stationary because the wires are not a complete circuit (connected to the battery).  Right: Same configuration but with circuit complete and iron fillings are then attracted to it. Photo: iStock

But Just What is This Magnetic Field?

If we pick up the other piece of iron (which does not have the copper wire around it) and place it near the iron piece that has the wire wrapped (and thus the electric current), that isolated piece of iron suddenly moves toward the electrified one.

The reason why the iron pieces attract each other is due to fact that the iron piece with the copper wire wrapped around it (called a coil) becomes magnetic. And so, we have just created an electromagnet

For the video below, you might want to put your thinking caps on as it explains pretty well how electromagnetic forces are derived (hint: when electrons move through a wire). We suggest those that are in school and/or have an absorption for learning continue on to this video.

For those that would like to bypass such items as Maxwell’s equations and just want a cheat sheet of what is the criteria for an electromagnetic field, see our summary below.

How Electromagnets are Made

An electromagnet can be made out of any type of metal, but iron and nickel are the ones most often used. Nickel magnets are stronger than iron magnets, but iron is cheaper. 

Iron is found in most scrap yards, or you can buy it from a hardware store. The first step in making an electromagnet is to create a wire that is wrapped with a coil of metal several times. This is known as an electromagnet coil. The coil has to be wrapped around a core, which is made out of a non-magnetic material. 

The Magnetic Field

A picture of a magnet
A permanent magnet which has the same properties as an electromagnet but without the current. Image by Francesco Bovolin from Pixabay

The electromagnetic field is the region of energy surrounding a magnet. The magnetic field is perpendicular to the path that the electrons flow.

Why are Electromagnets Important?

Electromagnets are important because they can be used to power items and devices that are used by us every day. Motors and generators are just two examples. They are also used in toys, as a way of moving things around in a car, or even to move things in a factory. 

They are also useful because they’re easily controllable. If you want to turn the electromagnet off, you simply turn off the electric current running through it. If you want to turn it back on, you can simply turn it back on again.

Types of Magnets

There are two types: temporary and permanent. Temporary magnets are only magnetic while electricity is running through them. Permanent magnets remain magnetic no matter what happens. This is because these magnets are not electrified. An example are the ones stuck to your fridge or another metal surface.

Conclusion

Magnetism is created when electrons are in movement. In a practical sense, this means that if you connect a wire to a battery (power source), electrons will move from the negative pole to the positive pole of the battery.

When this happens, a force is created in addition to the electrical force, which is the magnetic force. This magnetic force ‘pushes’ perpendicular to electrical force (current), so any metal that has magnetic properties will be attracted to this force and move towards it accordingly.

The magnetic force can be strengthened by any of the following criteria.

    • Taking the straight wire and curling it around the medium, usually an iron bar. The result is called a coil.
    • Wiring the coil more will cause the magnetic field to strengthen.
    • Increasing the current; that is, increasing the speed at which the electrons travel through the coiled wire will also strengthen the magnetic field.

The practical applications of electromagnets are the ability to cause an entity to move because of this force, such as what happens inside a motor.