- [Rob] Are you feeling curious?

- Yeah!

- Today on "Curious Crew."

Check that out.

Rev your engines as we take a spin.

Over 4,000 revolutions per minute.

Investigating the science behind electric motors.

Isn't that cool?

- [Narrator] Support for "Curious Crew" is provided by MSU Federal Credit Union.

From sweet peas to teens, MSUFCU offers you accounts that grow with children.

With financial education, gaming apps, and events, MSUFCU provides the tools and resources to make learning about finances fun and interactive.

Also by the Consumers Energy Foundation.

Dedicated to ensuring Michigan residents have access to world class educational resources.

More information is available at consumersenergy.com/foundation.

Consumers Energy Foundation, supporting education and building sustainable communities in Michigan's hometowns.

And by viewers like you.

Thank you!

(upbeat music) - Hi, I'm Rob Stevenson and this is-- - "Curious Crew."

- Welcome to the show, everybody.

We always like to start every episode with a couple of discrepant events because discrepant events stimulate-- - Curiosity.

- That's exactly right, and I've got some really fun ones for you today, and I'm gonna start by directing your attention right down here on the table.

I've got a double A battery, a really powerful neodymium magnet, and a bent wire.

Now, Carmela, I have a question for you.

What do you think will happen if I were to put the battery on the magnet and then connect the wire so it's sitting on the positive pole and touching the magnet on the bottom?

- I think there might be some kind of energy transfer that happens.

- Let's take a look.

So I'm gonna put this on, and you'll notice this neodymium magnet's gonna jump because it is really powerful.

Now let's carefully place this wire on top of the positive terminal, and check that out.

Isn't that neat?

Okay, now I've got another wondering for you, and I'm gonna ask this one for Kah'reice.

What might happen if I were to take the magnet and flip it the other direction?

- I think it'll spin in the opposite direction.

- So you're thinking if I switch the polarity of the magnet, maybe the wire will actually rotate in the opposite direction.

Oh, look at that one go!

Great prediction, Kah'reice.

Okay, I'm gonna stop it.

There's another device I wanna show you here on the table, and I'm gonna challenge you to see if you can reverse engineer it to figure out how it works, okay?

And I'm just going to put in this final battery so we have a closed circuit, and you watch what happens there.

(motor buzzing) All right, we got this thing humming right along.

I'm going to bring this last little piece in and bring it in really closely.

And suddenly the whole thing stops.

Isn't that strange?

Now, I'm gonna invite three of you to do a little scientific modeling.

So who wants to do a little modeling moment today?

Okay, Rishabh, Tauren, and Ian, I'm gonna have you three do it.

Anybody have a guess what we're gonna be investigating in this episode?

What do you guys think?

Janellyn, you got a guess?

- Does it have something to do with magnets and motors?

- Very good thinking.

We're actually talking about electric motors, and we're gonna explore this conversion from electrical energy into mechanical energy.

Stick around.

This episode's sure to get your motor running.

(upbeat music) - It seems kind of strange that the spinning wire can rotate with just a battery, a magnet, and a bent wire.

- I know.

When I think of electric motors, I imagine something much larger or more powerful.

That one's really too small to do much work.

- The other motor was a lot more powerful, and it used less batteries to make work.

I also noticed it was an electromagnet coil, so it's definitely using a magnetic field.

(upbeat music) - We use electric motors every day in our fans, washing machines, refrigerators, vacuum cleaners, toys, and electric cars.

The amazing thing about electric motors is that they convert electrical energy into mechanical energy, usually making an output axle rotate.

Through the work of great scientists like Andre-Marie Ampere, Michael Faraday, William Sturgeon, and Joseph Henry, they explored the connection between electricity, magnetism, and movement.

Now let's get rolling.

(electronic music) Now, if we want to understand electric motors, we need to back up a little bit and really start to discover the relationship between flowing electricity and magnetism.

Now Kah'reice, I know you've got some ring magnets right there.

Do me a favor, can you put them down on the table and see what happens when those similar poles come together?

So we get some good repulsion going on.

Excellent.

Janellyn, you also have some cars with some magnets taped to the front.

Can you show us what happened when those similar poles come together there?

Excellent.

And we can really see that result with those freely flowing wheels.

Now, something to keep in mind, these are made with permanent magnets.

Electric motors actually make use of both permanent magnets and temporary magnets.

So let's think about temporary magnets.

I've got this ordinary nail right here.

As it is, it is not magnetic at all.

However, you'll notice we've got a wire that wraps around the nail.

If I turn on the power supply and send electricity through the wire, I can turn this into a temporary magnet.

Once we have flowing electricity, it creates a magnetic field.

And I can make this stronger with more coils, more power.

So let's think about this another way.

We've got some evidence of that electromagnetic effect, but I wanna show it to you with a battery and some magnets.

I've got lithium battery here and a stack of very powerful neodymium magnets that I'm going to slide apart and separate, and I'm even going to rotate them so that they would repel.

I'm gonna place them on either end of this lithium battery.

Now, Janellyn, if I were to place this entire system inside this coil of wire so that the wire actually touches both ends of the magnets, what will happen?

- Are you gonna create a short circuit and magnetic fields?

- Now, if I create a magnetic field, this temporary magnet will react with the permanent magnets.

And if I do that, Kah'reice, what may happen?

- It might shoot through the tube.

- Let's take a look.

That was a really good prediction, Kah'reice.

This is already getting warm.

Now, you talked about a short circuit because this is actually flowing electricity consistently in there.

Let's do it one more time.

Now, if I'm careful and I hold it really tightly, I might be able to go right through the seam and it keeps going.

So what we have happening is the magnets are actually pushing and pulling its way through the system, which is pretty cool.

In fact, it's a regular battery train.

It seems strange to think that flowing electricity will make a magnetic field, but Hans Orsted, a Danish physicist accidentally made that discovery in 1820.

He showed how a wire carrying electricity would make compass needles line up with the generated magnetic field.

In 1829, Joseph Henry discovered that he could increase the strength of an electromagnet by wrapping a lot of wire coils around an iron core.

And he made an electromagnet that could support 2063 pounds.

These discoveries contributed to the development of electric motors.

(electronic music) So we've got some great DC motors we're gonna explore next.

What are the materials we have for the first one, Ian?

- A battery, a wire, a screw, and some really, really strong magnets.

- Yeah, so let's start putting these together.

And in fact, I have one extra piece that I'm gonna put on mine with these LED lights just to make it a little bit easier to see the effect.

Now we're gonna stack ours together.

You guys can go ahead and do yours.

And you'll notice as soon as we do this, this magnetic field already starts going right straight up through the screw up into the battery.

Now I'm gonna try to hold this on this negative end and see what happens when we come in close.

Oh my gosh, check that out.

Oh, you guys are doing a great job.

Now this is called a homopolar motor.

It's a DC direct current motor that results in this rotational movement.

The tricky part is, why does it even rotate?

So we know we've got this magnetic field that comes up from the magnet up through the battery.

At the same time, when I connect the wire, we've got current moving out through the side of the magnet.

The result is an additional force called the lorentz force, which goes in a totally different direction, and that's why we see the whole thing start to spin.

It's really cool, but it's not a very efficient motor.

But let's look at some more efficient DC motors.

First thing I'm gonna point out to you is we've got a north and south pole.

And you can see how those colors sort of extend right around the entire thing.

So we've got north on one side, south on the other side.

This is the permanent magnet part of the electric motor.

We also have a temporary magnet right inside.

You can see those windings.

And of course, as soon as we put electricity through there, we're gonna create a magnetic field.

So we can get the permanent magnetic field and the temporary magnetic field to react to each other.

Now this outer part, it doesn't move.

It's called the stator, okay?

It stays out.

The inside that rotates is called the rotor.

But there's one more part that becomes so fascinating over here on the end.

If we look on the end of the axle, we see these little stacks, these are called brushes, and they're going to pass the electrical charge right into the axle.

But can you guys see that there's a little gap right between those two pieces of metal.

This is because as it rotates, the brush touches one piece of metal, and then it touches the opposite piece of metal.

And what that does is it alternates the current.

So it hits north pole, south pole, north pole, south pole.

And the result, check it out.

We can get some rotation in there.

Isn't that cool?

Now this one works on six volts.

Let me show you a couple more.

Look at that.

And if I increase the voltage, we can even see little sparks going on in there as the brushes touch the commutator.

Isn't that amazing?

DC motors are super efficient.

Imagine the loop of wire positioned between two opposite stationary magnets called the stator.

When the ends of the wire are connected to a battery, the energy flows through it and a magnetic field is generated.

But because the wire goes both out and back, the loop sides react differently in the magnetic field, making it rotate.

It wouldn't take long for the ends of the wire to get twisted.

To solve that problem, the motor uses the commutator around the axle, which allows the wire loop or rotor to rotate continuously by switching the direction of the current.

Great design.

(upbeat music) We're gonna talk about torque.

Stick around.

We're gonna learn all about it.

- The torque episode is also one of my favorites.

- Oh, nice.

Oh, you got really good height.

- We learned about torque, which lets you apply different amounts of force to an object using things like levers or gears.

I got to sit on this giant balance beam in the middle of the studio.

- Okay, yes, you're right.

- [Ian] And we kind of leveled it out to see how we could get a couple of different people to balance on there.

- That was really, really close.

- That was really fun.

We were just going up and down.

- We could actually call this the teeter torquer.

(upbeat music) (dramatic music) - [Announcer] STEM challenge.

- So have you guys had fun learning about the electric motors so far?

- Yeah!

- That's great.

Now I've got a fun STEM challenge for you today.

In fact, you are going to be making your own electric DC motor.

Now just to get you started though, this would be a commercial one.

And it works fairly well.

Now, normally this is supposed to rotate around, and it kind of does what it's supposed to do.

You gotta give it a little flick and sometimes it falls off.

So my challenge for you is let's see if you can make a better DC motor using some stuff at home.

Are you guys ready?

- Yeah.

- Let's try it.

- It's like, slipping off the battery.

We are making DC electric motors, and a little circle piece of paper as our base.

We are using a battery, Play-Doh, rubber bands, five magnets, metal brackets, and some wire.

- It kind of looks like a little monster.

It keeps falling.

Trying to keep the wire as tight as possible so that it's stable enough to spin on its own.

That's a bit challenging.

But when you do get it, it's really cool.

Ooh, there we go.

- I think it turned out really good.

I'm pretty proud of myself for that.

- I just keep spinning it.

It's really fun.

- So it looks like you guys are just about finished.

Carmela, what did you use for your contact points and how many magnets did you use?

- I was using these two metal poles for my contact points, and I had five magnets.

- Excellent.

Okay, how about you, Kah'reice?

- I was using four magnets, and I had wrenches for my contact points.

- Wrenches is a good idea.

Good conductor of electricity there.

How about you, Janellyn?

- I had two metal brackets for my contact points, and I had two magnets.

- And you all got it to work, nice job.

I've all done it myself here, and I used just paper clips.

I'm gonna put this in there and see if we can get it spinning.

Ooh, it took right off.

How about that?

Isn't that fun?

You can try making your own electric DC motor.

If you have access to a digital tachometer, you can even measure how fast it's going.

Pretty cool, right, you guys?

- Yeah!

- We made some great little motors, but if we need more turning force, we need more torque.

T increase the rotational force, we could use more powerful permanent magnets, increase the current flowing through the wires, or use thinner wires with many more windings instead of thicker wires with fewer turns.

If the permanent magnets were curved and closer to the coil, that tube could increase the rotational force from the motor.

Ready for lift off.

(electronic music) So I've got a couple more motors I wanna share with you guys, and I wanna start with this one right here.

Rishabh, when you look at this motor, is there anything that you recognize?

- I see a few magnets involved, like the electromagnet over there and a few permanent magnets.

- Okay, great.

There's something else I want you to see as well, and it's in this little glass tube right over here.

Tauren, if you look really closely, I'm just going to swing this around and move it back and forth.

And what do you notice those little metal plates doing in there?

- They're coming together and then falling apart.

- See them bouncing back and forth?

This is called a reed switch.

And whenever you have a magnet that is near the reed switch, those two metal plates become magnetized, and they stick together.

Now, if I roll it over just a little bit, those metal plates open back up and it could actually turn off the switch.

Now that's really important for what we're gonna look at now.

This is a DC motor, and there's no brushes involved, okay?

In fact, once we power this up, the electromagnet is a magnet, and we end up having it set up so that the temporary magnet and the permanent magnet are gonna repel.

So it's going to try to push it away.

As soon as it pushes away, that reed switch opens up, turns off the electromagnet and it's just gonna keep spinning.

So take a look at what happens.

This is a pretty efficient little motor.

I have a little propeller that I put on the end on that output axle.

Now, this one's running on six volts, okay?

I would like to look at an AC motor.

We haven't explored that much.

AC motors are going to be, this one, in fact, is gonna be running off of 115 volts, and I've wired this up so I can use it safely.

But I want you to think about some devices around your house, Tauren, that you would plug in and you might have a spinning part.

Can you think of anything?

- A fan, maybe a refrigerator and a vacuum.

- Those are all really good examples, and all of them use AC motors when you plug them in.

Now, what's really interesting about an AC motor, I'm not using permanent magnets like we saw before.

This is actually going to be a temporary magnet, and I've got two coil windings in the stator.

What this does, as soon as we send power into it, it creates a rotating magnetic field.

And so the rotor inside starts to spin.

Now I've got a foot pedal here, and I'm going to fire this up and you can see, not only does it go incredibly fast, it's really quiet.

I have a question for you, Rishabh.

Where do you think I got this motor from?

- A fan.

- You totally guessed right.

And of course, I had to replace it with a wonderful "Curious Crew" logo.

Now we know that DC motors, super efficient, but AC motors, really strong, higher torque, and they can last a really long time.

We use electric motors every day, and the number of electric cars and buses on the road increase every year around the world.

Many of them are powered by an induction motor, a design that was invented by Nikola Tesla in 1887.

The stator in this design causes a rotating magnetic field that induces electricity on the conducting bars in the rotor causing it to spin.

The battery series produces direct current, and in this car, is converted to alternating current through an inverter, regulating the input frequency that determines the speed of the wheels.

The electric model is efficient, powerful, and quiet.

Thanks, Tesla.

(dramatic music) - Are you curious about careers in science?

Hi, I'm Janellyn, and with me today is Hannah Maloof.

Hannah, tell me where you are and what you do.

- Hi, Janellyn.

I'm here at my family's race car shop, Maloof Racing Engines in Los Angeles, California, and I build racing engines, I professionally drive, and I also do stunts.

My dad has been building engines his whole life, and he showed me the trade.

Ever since I was little, I've by his side learning everything I could.

There is a lot of STEM involved in building engines.

You order all these parts, hundreds of parts, and then all the detail and calculations that go into assembling it.

And then once you start it and it runs and it breathes and you put it in the car, you take that car and it performs exactly how you want, that's rewarding.

- This pit stop with engine builder Hannah Maloof has reached the finish line.

Explore your possibilities!

(dramatic music) And now, back to "Curious Crew."

- Woo!

(electronic music) (upbeat music) - So we know that both motors use magnets to get them working.

A permanent one with the spinning wire and a electromagnetic in the other one.

- And Carmela and I saw how the suspended spinner was a homopolar motor.

It works the same way as the spinning wire when the circuit's complete.

- I think the other motor used a reed switch.

Like the one Dr.

Rob showed us.

You could just see the magnets in that example.

- So have you guys had fun investigating electric motors today?

- Yeah!

- Now I know several of you have been hard at work thinking about these discrepant events from the beginning of the show, and you've had some electric conversation, but what have you figured out about the spinning wire, Rishabh?

- We think that this is an example of a homopolar motor that uses current and a magnetic field to get the wire to spin.

- That's exactly right.

Homopolar motors have been around a long time.

Michael Faraday made the first one back in 1821.

It didn't look anything like this, but you've hit on a couple of key ideas.

As soon as we put the battery on top of the magnet, we actually get the magnetic field going up into the battery.

Then when we combine the wire, we end up having the current go down and out towards the side of the battery.

This actually creates a force going up and another force going to the side, which ends up creating a third force, which is called the lorentz force, and that's what we see as the spinning wire.

Let's do it one more time here.

This one's got a totally different arrangement.

Now, Tauren, do you think this is gonna last a long time?

- Probably not because you created a short circuit and it drains the battery pretty quickly.

- You're exactly right.

They will drain quickly because short circuits also get a hot system, but it sure is fun to watch in the meantime.

Now, if you wanna make your own homopolar motor, you might wanna think about making sure that the wire that you bend has a very small contact area so we can reduce the amount of friction.

And finally, if you use a nail set, you can dimple the positive end of the battery, which gives it a nice place for it to rest while it's spinning.

Pretty cool.

How about this other device?

Ian, were you guys able to reverse engineer this device?

- We think so.

There's an electromagnet that can get powered up, but we think there's also a reed switch that can get it rotating by turning on off the electromagnet.

- The reed switch is really important.

We've looked at a lot of DC motors where there are brushes involved.

This one doesn't have any brushes, so we need some way to start and stop that magnetic field.

Now what happens here is we've got these teen tiny metal plates down in that reed switch.

And when they're near a magnet, they magnetize and stick together.

That actually completes the circuit so the electromagnet can turn on.

Now, if I rotate it this way just a little bit, you have probably figured out we have magnets underneath this ring.

And when we have this powered up, it's going to repel from the temporary magnet and force this ring to turn slightly.

As soon as it turns, that reed switch opens up, it turns off the power, but the momentum keeps it going, closing the reed switch again, turning on the power, repelling the magnet, and it goes on and on.

Now, I'm gonna get this going one more time.

So I'm gonna measure the rotation right here on the top.

This is actually going over 4,000 revolutions per minute, you guys.

To stop it, I can actually bring in another magnet, and it completely disrupts the magnetic field and stops the entire system.

Pretty amazing, don't you think, you guys?

- Yeah!

- So keep this in mind, whenever you see a device spinning at your house, it's very likely an electric motor is responsible.

So remember, my friends.

- Stay curious!

- And keep experimenting.

Get your Curiosity Guide and see more programs @wkr.org.

- [Narrator] Support for "Curious Crew" is provided by MSU Federal Credit Union.

From sweet peas to teens, MSUFCU offers you accounts that grow with children.

With financial education, gaming apps, and events, MSUFCU provides the tools and resources to make learning about finances fun and interactive.

Also buy the Consumers Energy Foundation.

Dedicated to ensuring Michigan residents have access to world class educational resources.

More information is available at consumersenergy.com/foundation.

Consumers Energy Foundation, supporting education and building sustainable communities in Michigan's hometowns.

And by viewers like you.

Thank you!

- Do you think this is gonna last a long time?

- Probably not because you created a short circuit.

(stutters) - But we think there's also a reed switch that can get, meh.

The suspended spinner was a, suspended spinner.

That was like a tongue twister.

- And then we'll take it higher.

(upbeat music) Carmela was just getting into it.

(soft music)