Physics Girl

So we're going to be able to rip apart this can with just electromagnets?

JOE: That is correct.

JOE HANSON: Um, why?

JOE: For science.

I'm here today with Joe Hanson.

And we're here with Arc Attack.

JOE HANSON: So wait, wait.

How fast does this happen?

How does this work?

What-- what is this?

This is a can crushing machine, in which we will use a magnetic field to sear this aluminum can in half and send it off in two directions.

Can we rip some cans apart?

We absolutely can.

[click] 3, 2, 1.

[snap] Whoa!

Whoa, that was-- that was awesome!

That was loud.

[explosive sound] [explosive sound] [laughther] JOE HANSON: Um, wait.

So why do you have this?

So we do educational shows for kids.

And this machine is just an extreme way that we can demonstrate how electromagnets work.

DIANNA COWERN: We should have mentioned, Arc Attack is a performance group.

JOE HANSON: And a pretty awesome band.

If you've never heard of Arc Attack, you're missing out.

They play singing Tesla coils.

DIANNA COWERN: The bolts of lightning are the instruments.

But the members of the group are also a bunch of engineers, who like to make cool things, like this device.

JOE HANSON: So this isn't like a trick.

There's nothing it's like chopping the can in half.

No.

So the can is actually tearing itself apart.

So do you explain that to the kids in your shows?

Well, yeah.

It's a science show, not a magic show.

So how does this device work?

We want the overview.

OK.

So we have a coil of wire right here.

And we put the aluminum can inside the coil of wire.

And then we put an electric current into this coil of wire, which creates a magnetic field.

DIANNA COWERN: This is one of those weird properties of electromagnetism.

An electric current that is flowing charges always creates a magnetic field.

Which direction is that magnetic field pointing?

OK, we talked about this earlier.

I'm testing you.

It's the right hand rule.

So if the current is going this way, then we get a magnetic field just like my fingers all the way around that coil, right?

Very good.

Yes.

So it's like a toroidal shape, like a donut.

Hm.

I can understand donuts.

That donut-shaped magnetic field is getting stronger.

It's changing as the current increases.

And another weird property of electromagnetism is that changing magnetic fields near a conductor can induce currents.

DIANNA COWERN: We can see that here with another cool demo Arc Attack has, where you drop a magnet through some coils of wire attached to LED lights.

The LEDs light up, because the magnetic field going through induces a current.

No batteries required.

JOE HANSON: But those currents also have their own magnetic field.

So we induce a current in the can with the first magnetic field.

But that current induces a second magnetic field.

And it's facing the same way as the first, which means you have two very strong magnets with like poles which want to get away from each other.

But the can has nowhere else to go but inward.

So the magnetic field actually sears the can in half and sends it off in two different directions.

That's what makes the boom boom happen.

That's what makes the boom boom.

That was awesome.

There's a lot you can do with induction, though.

And you guys are engineering geniuses.

So I think you must have something else up your sleeve.

We can use an electromagnet to launch this aluminum ring into the air.

DIANNA COWERN: This demo takes aluminum, which doesn't normally feel any push or pull from a magnet, and turns it into an electromagnet by inducing a current in the aluminum ring.

With another electromagnet below pushing it with a lot of force, we should see it fly up in the air.

Something tells me we're going to need these.

Goggle up.

JOE: 3, 2, 1 and-- [snap] Whoa!

That was awesome.

Wow.

OK. All pretty cool.

But I feel like you're holding out on me, because Joe told me last time he was here he left with a shrunken quarter.

You weren't supposed to say anything.

All right, I'll tell you what, follow me.

All right.

Cat's out of the bag.

JOE: So basically, we have a quarter that's wedged between two pieces of 1-inch dowel, and it's got some wire wrapped around it.

And it's hooked up to these electrodes.

And we're going to put the steel blast chamber on it.

And then we're going to put the pin through there.

And then we're going to take the wooden chamber.

And-- DIANNA COWERN: This is serious business.

JOE: Yeah, this one is a lot more energy than what we did with the can.

And then we're going to stand behind Dianna.

[laughter] We got this set to 80%.

And then we push this button.

So they'd be ready for the bang?

Or will we know something's going to happen?

Is there going to be a bang?

I'll tell you, there's going to be a bang.

There's going to be a bang?

It is going to be a bang.

Oh, geez.

OK. Let's go!

It's already.

Oh, it's ready?

You guys ready for this?

Everybody good?

[bang] Whoa!

That was a huge explosion.

That was a huge explosion.

So when it exploded like that, I think sparks underneath that steel chamber, underneath this wooden box.

Yep.

And what happened in here?

Well, we're about to find out.

So first, let's unplug the thing, so it doesn't accidentally turn on, because this is the kind of shock that it would only happen to you once in your life.

DIANNA COWERN: Whoa!

JOE HANSON: Whao!

DIANNA COWERN: Oh, that is real smoke.

Whew!

Oh, my gosh.

It's a-- it's a metallic smell.

Oh, my gosh.

JOE HANSON: It's-- it's really hm.

DIANNA COWERN: Oh, whoa!

JOE HANSON: Are we sure there's still a quarter in there?

JOE: Yeah.

We just got to poke around and find it.

Oh, gosh!

Oh, there he is.

Ouch.

Ouch.

DIANNA COWERN: Isn't that a little hot?

Oh my, look at that thing.

And that is how you shrink the head.

That's amazing.

JOE: Yeah, it's pretty crazy.

DIANNA COWERN: Whew, that was awesome.

That was an incredible set of physics demos.

And we haven't even gotten to the Tesla coils.

But you can check those out in all of their glory over on Joe's channel, It's Okay To Be Smart.

We're going to figure out how those things can make music.

It's going to be awesome.

And thank you so much to Arc Attack for having us here.

They're amazing.

You can check them out on Facebook.

And last but not least-- [classical music playing] [bang] [bang] [bang] [bang] [bang] [bang] Let's take a bow.

[applause] Well done.

That was very nice.