How does an Electric Motor work? (DC Motor)

Summary

This educational video script explores the fundamental concepts of electricity and magnetism, leading to a clear explanation of how electric motors operate. It begins with the basics of circuits and switches, moves on to the properties of magnets, and then demonstrates how a spinning magnet can be used to create motion. The script then delves into electromagnets, explaining how they can be turned on and off, and how their polarity can be reversed. It culminates in a step-by-step construction of a simple electric motor, highlighting key components like the armature, commutator, and stator. The video aims to inspire curiosity and learning, especially in the fields of math and science, and encourages viewers to explore further with resources like Brilliant, a problem-solving platform.

Takeaways

• 🔌 Understanding Circuits: Electricity flows through a circuit consisting of a battery, wires, and a device like a light bulb. The path must be complete for the circuit to work.
• 🔄 Switching Current Direction: Flipping the battery changes the direction of the current flow, affecting how some devices operate.
• 🧲 Basics of Magnetism: Magnets have north and south poles that attract and repel other magnetic objects, and permanent magnets are always 'on'.
• 🔧 Electromagnet Creation: By wrapping a wire around a metal bolt and creating a circuit, you can create an electromagnet with controllable on/off properties.
• 🔀 Reversing Electromagnet Polarity: Changing the direction of the current in an electromagnet reverses its polarity, switching the north and south poles.
• 🌀 Principle of Motor Rotation: A spinning electromagnet can be created by continuously reversing the polarity of an electromagnet, causing it to keep spinning.
• ⚙️ Motor Construction: An electric motor is built with a stator (stationary magnets) and a rotor (spinning armature), with the armature often having multiple loops for continuous motion.
• 🔄 Commutator Function: A commutator with brushes automatically switches the current direction in the armature, allowing the motor to spin continuously without manual wire switching.
• ⚙️ Multi-loop Armature: Adding more loops to the armature and splitting the commutator helps maintain a smooth and continuous spinning motion.
• 💪 Improving Torque: Increasing the number of wires in electromagnets and using more electricity can enhance the motor's torque, leading to a faster spin.
• 🔧 Motor Application: The spinning motion of an electric motor can be converted into various types of movement for different devices, such as toys, fans, or cutting knives.

Q & A

What are some common household devices that use electric motors?

Some common household devices that use electric motors include kids' toys, table fans, toothbrushes, hairdryers, and electric cutting knives.

What is a circuit and why must it be complete for electricity to flow?

A circuit is a closed loop through which electricity can flow, consisting of a battery, wires, and a device that uses electricity like a light bulb. The path must be complete for the circuit to work; otherwise, the electricity stops flowing and the device does not operate.

What is the significance of the direction of conventional electric current flow?

Conventional current flow is considered to flow from the positive to the negative terminal of a battery. However, electrons actually flow in the opposite direction. The direction is significant because some devices will work differently depending on which way the current flows.

What are the basic properties of a magnet?

A magnet has a north pole and a south pole. It attracts other metal objects and has the property that opposite poles attract each other while the same poles repel each other.

What is a permanent magnet and how is it different from other types of magnets?

A permanent magnet is always 'on' and cannot be turned off. It is made up of smaller magnet domains that are aligned in the same direction. Unlike temporary magnets, permanent magnets retain their magnetic properties.

How does the concept of a spinning magnet relate to the working of an electric motor?

The spinning magnet concept is fundamental to electric motors. When a magnet is brought near another magnet, it aligns itself due to the attraction and repulsion of poles. This principle is used in motors to create a continuous spinning motion.

What is an electromagnet and how is it created?

An electromagnet is a type of magnet that is created when a current flows through a wire wrapped around a metal bolt. The magnetic domains in the bolt align due to the current, creating a temporary magnet with a north and south pole that can be turned on or off.

What is the process of reversing the polarity of an electromagnet?

The polarity of an electromagnet can be reversed by flipping the battery or switching the wires connected to the electromagnet. This changes the direction of the electric current, which in turn switches the north and south poles of the electromagnet.

What is the purpose of a commutator in an electric motor?

A commutator is a part of the electric motor that helps to maintain continuous spinning motion. It is a ring with gaps that rotates with the armature, and it automatically switches the electrical connections as the armature spins, reversing the polarity of the electromagnet and ensuring smooth operation.

How does adding more loops to the armature improve the performance of an electric motor?

Adding more loops to the armature creates more electromagnets, which can take turns being active. This ensures a continuous and smooth spinning motion, improving the motor's performance and torque.

What is torque in the context of electric motors and how can it be improved?

Torque is the spinning force on the armature of an electric motor. It can be improved by increasing the number of wires wrapped around the electromagnets, using more electricity, or adding more loops to the armature, all of which contribute to a stronger and faster spinning motor.

Outlines

00:00

🔌 Basics of Electricity and Magnetism

In this paragraph, Jared introduces the concept of electric motors and their ubiquity in everyday devices. He then delves into the fundamentals of electricity, explaining the role of circuits, batteries, wires, and switches in creating a complete path for electricity to flow. The video also covers the principles of magnetism, including the properties of permanent magnets, their ability to attract metal objects, and the interaction between magnetic poles. Jared demonstrates how a spinning magnet can be created and the importance of this concept for understanding electric motors. He further explains how an electromagnet is made by wrapping a wire around a metal bolt and creating a circuit, which can be turned on and off, unlike a permanent magnet. The paragraph concludes with a demonstration of how reversing the polarity of an electromagnet can change the direction of its poles.

05:01

🔧 The Working Mechanism of an Electric Motor

This paragraph focuses on the inner workings of an electric motor. It begins with a simplified model of a motor using electromagnets and a spinning magnet to illustrate the basic principle of motor operation. Jared then introduces the concept of the armature and explains how it can be used in conjunction with electromagnets to create a continuous spinning motion. A key component called the commutator is added to the armature to automate the process of polarity switching, which is essential for maintaining the motor's rotation. The paragraph also discusses the importance of the number of loops in the armature and how they contribute to the motor's speed and torque. To enhance the motor's performance, Jared suggests increasing the number of wires in the electromagnets and using a stronger power source. The video ends with an explanation of the terms 'stator' and 'rotor,' and a brief mention of different types of electric motors, including DC motors, which are commonly found in devices powered by batteries.

Keywords

💡Electric Motor

An electric motor is a device that converts electrical energy into mechanical energy, creating motion. It's the main theme of the video, as the script discusses how electric motors work in various household devices like toys, fans, and hairdryers. The video explains that when an electric motor is turned on, it starts rotating due to the interaction between magnetic fields and electric currents.

💡Circuit

A circuit is a closed loop through which electric current flows. In the context of the video, a basic circuit consists of a battery, wires, and a device like a light bulb. The script explains that electricity flows through the circuit only when the path is complete, which is controlled by a switch, and that the direction of the current can affect how certain devices operate.

💡Magnet

A magnet is an object that produces a magnetic field and has two poles, north and south. The video script uses magnets to illustrate the principles of attraction and repulsion, which are fundamental to the operation of electric motors. It also discusses permanent magnets, which are always 'on' and have their magnetic domains aligned, and how they can be used to create motion in a motor.

💡Electromagnet

An electromagnet is a type of magnet whose magnetic field is produced by an electric current. The script demonstrates how wrapping a wire around a metal bolt and completing a circuit can create an electromagnet with a north and south pole. The electromagnet is significant in the video because it can be turned on and off, unlike a permanent magnet, and its polarity can be reversed by changing the direction of the current.

💡Polarity

Polarity refers to the magnetic poles of a magnet, which are north and south. In the video, polarity is important for the interaction between magnets and electromagnets. The script shows that reversing the polarity of an electromagnet by changing the direction of the electric current can change the magnetic poles, which is crucial for the continuous rotation of the motor.

💡Armature

The armature is a part of an electric motor, typically a loop or series of loops of wire that rotates within the magnetic field. The script describes replacing a spinning magnet with an electromagnet and then using a metal loop, or armature, to demonstrate the basic principle of a motor. The armature is key to the motor's operation as it is the part that spins due to the magnetic forces acting upon it.

💡Commutator

A commutator is a component in an electric motor that helps to switch the direction of the current in the armature, thus reversing the polarity of the electromagnet and allowing continuous rotation. The video script explains that the commutator is a ring with gaps on opposite sides that spins with the armature, and brushes maintain contact with it to switch the current direction automatically.

💡Torque

Torque is the force that causes rotation in a motor and is a measure of how much the motor can rotate an object. The script mentions that adding more loops to the armature and using more electricity can improve the torque of the motor, leading to a faster spin. Torque is essential for understanding the motor's ability to do work and move objects.

💡Stator

The stator is the stationary part of an electric motor that the rotor (another name for the armature) rotates within. The video script refers to the stator as the two permanent magnets on the sides of the motor, which remain stationary while the rotor spins. The stator provides the magnetic field necessary for the motor's operation.

💡DC Motor

A DC motor, as described in the video, is a type of electric motor that uses direct current (DC) to operate. The script explains the basic construction and operation of a DC motor, including the use of a commutator and brushes, and how it can be used in various devices powered by batteries. The DC motor is a common type of motor found in many household and industrial applications.

Highlights

The video explains the basics of electricity, magnets, and how an electric motor works, using a simple and engaging approach.

A circuit consists of a battery, wires, and a device that uses electricity, such as a light bulb, with the path being complete for the circuit to work.

The concept of conventional flow and the ability of devices to work in both directions with the current flow being reversed.

Magnet explanation, including the north and south poles, and how opposite poles attract and same poles repel.

Permanent magnets are always on, made up of smaller magnet domains lined up in the same direction, and can't be turned off.

Demonstration of a spinning magnet using a permanent magnet with a hole in the center and a side magnet, showing how opposite poles attract and same poles repel.

Creating an electromagnet by wrapping a wire around a metal bolt and creating a circuit, which can be turned on or off like a light bulb.

Reversing the polarity of an electromagnet by flipping the battery or switching the wires, which can cause the magnet to start spinning.

The spinning electromagnet concept is crucial for understanding how electric motors work, with the ability to keep the magnet spinning by continuously switching the polarity.

Improving the torque of an electric motor by using stronger magnets and more wires, which results in a faster spin.

The addition of a commutator to an electromagnet's armature, which allows for continuous spinning by automatically switching the polarity of the electromagnet.

The importance of a split commutator ring and additional loops in the armature for a motor to maintain a continuous spinning motion, ensuring a smooth and regular speed.

The spinning force on the armature, called torque, is what makes the motor spin, with stronger torque leading to a faster spin.

Electric motors can be improved by using more wires and electricity, resulting in stronger electromagnets and faster spinning.

The parts of an electric motor, such as the stator, rotor, and the concept of DC motors, are explained, highlighting their roles in creating the spinning motion.

Electric motors can convert the spinning motion to other types of movement, like the side-to-side motion seen in a fan or an electric cutting knife, demonstrating their versatility and practical applications.

The video concludes with a plug for Brilliant, a problem-solving website and app focusing on math and science, emphasizing learning by doing and visual concepts.

Transcripts

- [Jared] If you look around your house,

you will see many devices that have electric motors,

such as kids' toys, table fans,

toothbrushes, hairdryers, and this electric cutting knife.

But how does the electric motor work?

You turn it on and somehow it starts rotating.

Why is that?

In this video, we'll cover the basics of electricity

and magnets and then put it all together

to understand how the motor works.

(buzzing)

(clanging)

This video is sponsored by Brilliant.

Let's start with something called a circuit.

You have a battery, some wires

and a device that uses electricity,

such as a light bulb.

Electricity flows through the circuit.

But as soon as there is a break in the wire,

the electricity stops flowing

and the light bulb goes off.

The path must be complete for the circuit to work.

This is best done through the use of a switch.

Electricity is flowing down the wire.

This is called conventional flow.

If we take the battery out and flip it,

then the current will flow the other way.

The light bulb will still work in either case

but there are some devices

that will work differently depending

on which way the current flows.

Okay, so that's the basics of a circuit.

Now let's come over here.

This is a magnet.

It has a north pole and a south pole.

And it likes to attract other metal objects

like these paperclips.

If you bring another magnet towards it,

opposite poles attract,

and the same poles repel.

The magnets don't have to be in this shape,

for example, some magnets might be more flat, like this.

You can think of this magnet as always on,

it's always working, you can't really turn it off.

That's why it's sometimes called a permanent magnet.

It's made up of any smaller magnet domains

that are lined up in the same direction

but later, I'll show you a type of magnet

where this not always the case.

Let's take one of our permanent magnets

and drill a hole in the center

and put it on something that will allow it to spin.

Now, bring another magnet towards it.

Our spinning magnet will immediately line up

until opposite poles are right next to each other.

Now switch out the side magnet.

The same poles repel and opposite poles attract.

If we keep switching out these side magnets,

then our spinning magnet will just keep spinning.

This concept of the spinning magnet is really important.

We'll come back to it in a moment.

Here's a metal bolt which is not a magnet.

It's made up of magnetic domains

but they're pointing in random directions.

Now let's take a wire,

wrap it around several times and then create a circuit.

The current through wires forces the magnetic domains

to line up.

That means we've just made a magnet,

or more specifically, an electromagnet.

It can do the same things that a permanent magnet can.

It can pick up pieces of metal

and it has a north and a south pole,

which will attract or repel other magnets.

But the electromagnet is special

in the sense that it can be turned on or off,

just like the light bulb.

You can't do that with a permanent magnet.

Now watch what happens when we flip the battery.

The electric current was flowing this way

but now it flows the other way.

This will cause the poles on our magnet to switch places.

North will become south

and south will become north.

This is called reversing the polarity of an electromagnet.

Instead of flipping the battery,

an easier way to do this

is to just switch the wires.

You should be aware that the electromagnet

will get very hot if it's on for a while,

just a caution in case this video inspires

any science projects.

Let's come back to our spinning magnet.

This time we'll replace the spinning magnet

with our electromagnet.

As soon as we connect the wires,

the magnet turns on and it lines up

with the side magnet.

Now, in reality, connecting these wires

would prevent the bolt from spinning freely

but what's important here

is the concept of the spinning electromagnet.

Now let's switch the wires to reverse the poles

on the electromagnet.

The same poles repel and opposite poles attract.

Now, reverse the polarity again.

Same poles repel and opposite poles attract.

If we keep switching the polarity,

our electromagnet will just keep spinning.

To make this strong,

let's bring in another permanent magnet on the side.

Notice how this side has the south pole

towards the center and this side

has the north pole towards the center.

The side magnets work together

to spin the one in the middle.

This right here shows the very basics

of an electric motor

but we need to make a few improvements.

The two side magnets can be replaced

with stronger curved magnets.

And instead of a bolt with wires,

we're gonna use a metal loop.

This is called the armature.

Connect our wires and we have a circuit again.

This time, you can think of the electromagnet

as flat like this with the south pole pointing up.

Now the armature will spin

until opposite poles are lined up.

We can keep it spinning

by switching the wires just like we did before.

But this is a lot of work to sit here

and manually switch these wires.

We need to add something

to the armature called a commutator.

It's a ring with gaps in the opposite sides.

The commutator will spin along with the armature.

Now we connect the circuit with two brushes on the side.

These brushes will slide along

as the commutator spins.

And they are spring loaded

so that they always maintain contact.

The current flows from the wire

through the brush, the commutator ring,

the armature loop and back through the other side.

Now we have our electromagnet and the armature spins.

As we come around this time,

the brushes will switch contact

to the other side of the commutator ring.

And remember, there's two brushes

so this is happening on both sides.

Before the switch,

the current in the armature is flowing this way.

After the brushes switch sides,

current will flow the other way.

This means the electromagnet switches polarity,

which will cause the armature to keep spinning.

This commutator ring does the same thing

as switching the wires like we were doing before

but this time, it does it all on its own.

It will continue to spin

as long as we're connected to a battery.

Disconnect the battery, no more electromagnet

and the spinning stops.

Now, so far, we've only used one loop on the armature.

This will cause our motor to have an irregular speed

and in fact, we could get stuck in this position

with the brushes halfway between commutator segments.

What we can do is split the commutator ring

and then add another loop,

so first, the brushes are in contact

with these commutator segments,

which turns on this electromagnet,

which causes it to start spinning.

Once we get to here,

the brushes switch contact

to the next pair of commutator segments,

which means this loop turns off

and the next loop turns on.

Now, this electromagnet wants to spin.

The brushes switch contact

and the next loop turns on.

This keeps happening as our motor spins.

It's almost like the loops

will take turns being an electromagnet.

Some electric motors will add many loops to the armature.

This ensures that there will be a continuous spinning motion

on the motor.

This spinning force on the armature is called a torque.

Stronger torque means a faster spin.

There are some things we can do to improve the torque

of the motor.

Electromagnets are stronger when there are more wires.

This is true when we wrap more wires

around the metal bolt

and it's also true when each of our armature loops

are made of many wires.

The motor will have stronger electromagnets,

which means it will spin faster.

If you look at some pictures

of real electric motors,

you can see lots of wires wrapped around

and yes, this is the same reason.

More wires wrapped around means stronger electromagnets.

Another way to make this stronger

is to use more electricity.

Let's learn a few more terms here.

The part that doesn't move is called the stator.

In this case, it's the two permanent magnets on the side.

These fit inside the edges of the motor case.

The armature in the middle is also called a rotor.

Remember, this is the part that spins.

The axle goes through the middle here

and then sticks out the back of the motor.

What I've shown you in this video

is called a DC motor.

If you have a device that moves

and is powered by a battery,

there's a good chance there's DC motor in it.

Other types of electric motors

will work a little differently than what I've shown here.

No matter the type of motor,

most of them will produce some type

of spinning motion.

Once it's spinning,

we can use this to make different devices move.

In this case, a kids' toy.

Or even a fan that cools your room.

The spinning of the motor

can be converted to other types of movement,

such as the side-to-side motion that we see in this fan.

Or how about this electric cutting knife?

Each blade is going back and force.

It all starts with the spinning of the motor

to turn a gear,

which then pushes these two pieces back and forth.

So hopefully this video has made a few light bulbs go off

in your brain.

If you like learning new things,

head on over to Brilliant.

This is a problem-solving website

and app that focuses specifically on math and science.

The idea here is that you learn by doing.

Pick a topic, it starts with the basics

but gradually gets more complex as you go.

For me, I've enjoyed how you can see

these concepts visually,

like the area of a circle.

You get to see why the equation works.

The best way to learn is to do it yourself.

Master the concepts by solving fun

and interactive problems and look at that,

they've even got a course on electricity and magnetism.

You can learn more about the concepts you've seen

in this video.

Brilliant is great for anybody that is curious

and likes to learn new things,

whether you're a student learning it

for the first time or a professional

who wants to keep their skills sharp.

Sign up for free by going to brilliant.org/jaredowen.

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