磁铁是如何工作的？

ABC，听好了。

ABC, listen.

你好。

Hello.

我在这儿。

Nid here.

今天在《想象一下》节目中，我要把一些照片贴到冰箱上。

And today on Imagine This, I'm sticking some photos to the fridge.

我们把这张我酷酷冲浪的照片贴这儿，再把这张我穿着白大褂酷酷的照片贴这儿。

Let's put this one of me looking cool surfing over here and this other one of me looking cool with my lab coat over here.

为什么有这么多？

Why are there so many?

等一下。

Hang on.

哦，不。

Oh, no.

你的磁铁用完了。

You're out of magnets.

但我还有很多我想贴上去的酷炫照片。

But I still have heaps of cool photos of me that I wanna stick up.

你能再做一个磁铁吗？

Can you make another magnet?

你觉得磁铁是用什么做的？

What do you think magnets are made of?

我觉得磁铁是由磁性岩石和不同种类的金属制成的。

I think they're made of magnetic rocks, different types of metals.

这个勺子是金属的，也许我可以拿它来代替。

This spoon is metal, so maybe I could use this instead.

代替。

Instead.

不行。

No.

不行。

No.

为什么？

How come?

因为勺子里面没有磁性物质。

Because there's nothing magnetic in the spoon.

我觉得是因为它不是同一种金属之类的。

I think it's because it's not the same type of, like, metal or something.

大多数金属都有磁性，但并不是所有金属都有。

Most metals are magnetic, but not all of them.

我知道。

I know.

如果我把它扔出去呢？

What if I throw it?

好吧。

Alright.

试试看。

Give it a try.

不行。

No.

没成功。

It didn't work.

太重了。

Too heavy.

我们收到很多关于磁铁的问题。

We've had lots of questions about magnets.

你好。

Hi.

我叫基拉，七岁。

My name's Kiera, and I'm seven years old.

我叫奥利，五岁。

My name is Ollie, and I'm five years old.

我叔叔叫塔米，我八岁了。

My uncle Tammy, and I'm eight years old.

我叫索菲。

My name is Sophie.

我六岁了。

I'm six years old.

我叫弗雷德，我七岁了。

My name is Fred, and I'm seven years old.

我叫吉米，我七岁了。

My name is Jimmy, and I'm seven years old.

嗨。

Hi.

我是奥斯卡。

I'm Oscar.

我七岁了，我想知道磁铁是怎么制造的？

I'm seven years old, and I'd like to know how are magnets made?

磁铁是怎么工作的？

How do magnets work?

为什么它们会相互推和拉？

Why do they push and pull?

它不像胶水那样粘吗？

It's not sticky like glue, is it?

也许是滑动？

Maybe slide?

也许是振动来了，然后就粘住了。

Maybe vibration comes and it sticks it.

里面是金属磁性材料。

Metal magnetic beams inside it.

我知道谁可以教我们关于磁铁的知识，凯西·福利博士。

I know who can teach us about magnets, doctor Kathy Folly.

她是一位物理学家，也是磁铁方面的专家。

She's a physicist and an expert in magnets.

她甚至还是澳大利亚的首席科学家。

She was even the chief scientist of Australia.

那老板是所有科学家吗？

And boss are all the scientists?

差不多吧。

Kinda.

这是全国最高的科学职位。

It's the top science job in the whole country.

我们去凯西的办公室看看吧。

Let's go visit Kathy in her office.

你好，福利博士。

Hi, doctor Foley.

你好，凯西。

Hi, Kathy.

大家好。

Hi, everyone.

见到你真好。

Lovely to see you.

凯西，你手里拿的是什么？

What have you got in your hands, Kathy?

是的。

Yeah.

你在玩什么？

What are you playing with?

哦，这些只是一些小磁铁。

Oh, these are just some little magnets.

它们在我思考时让我双手不闲着。

They keep my hands busy while I think.

我们就是来问你这个的。

That's what we came to ask you about.

是的。

Yeah.

磁铁是什么？

What are magnets?

它们是怎么工作的？

And how do they work?

嗯，磁铁有各种形状和大小，而且用途很多。

Well, magnets can come in all shapes sizes, Well, and they're used in lots of ways.

但我什么也看不见。

But I can't see anything.

磁力在哪里？

Where's the magnet power?

我们需要仔细看看发生了什么。

We'll need to take a closer look at what's going on.

那我们不妨发挥想象力，把磁铁放大看看？

So how about we use our imaginations to magnify these magnets?

是的。

Yeah.

我们把它们变得特别大吧。

Let's make them really big.

对。

Yeah.

一、二、三。

One, two, three.

飞起来的订书机。

Flying stapler.

鸭子。

Duck.

小心网。

Look out for the web.

还有那些回形针。

And those paper clips.

所有办公用品都被吸到磁铁上了。

All the office stuff is flying into the magnets.

发生什么事了？

What's happening?

因为里面还有其他磁铁。

Because there's other magnets inside.

正确。

Correct.

所有磁铁都有一个叫做磁场的东西。

All magnets have something called a magnetic field.

磁场？

A field?

上面没有草。

There's no grass on them.

没有。

No.

磁场是你可以感受到磁铁那种无形推力或拉力的区域。

The magnetic field is the area where you can feel that invisible push or pull of a magnet.

它们会相互吸引和排斥。

They stick together and push away.

有时候，更大的磁铁具有更强的磁场。

Sometimes the bigger magnets have a stronger magnetic field.

所以我认为当我们把磁铁放大后

So I think when we supersized our magnets

我们让它们变得更强大了。

We made them more powerful.

然后附近所有其他磁性物体都被吸了过来。

And then every other magnetic object nearby was pulled in.

但这个金属订书机平时并不是磁铁。

But this metal stapler isn't normally a magnet.

对吧？

Right?

或者这些回形针？

Or these paper clips?

它们不会粘在冰箱上。

They're not gonna stick to the fridge.

不会。

No.

这些物品被称为临时磁体。

These items are what we call temporary magnets.

它们由能在短时间内被磁化的金属组成。

They're made up of metals that can be made magnetic for a short time.

桥形磁体和这些条形磁体被称为永久磁体，因为它们能长期保持磁性。

Bridge magnets and these bar magnets are called permanent magnets because they stay magnetic.

非常酷。

Very cool.

钕在保持磁性方面非常出色。

Neodymium is very good at staying magnetic.

所以你熟悉的大多数磁体都是由这种材料制成的。

So this is what most of the magnets you're familiar with are made of.

磁铁的一端我们称为北极，另一端称为南极。

One of the ends of the magnet we call the North Pole and the other the South Pole.

所有企鹅都在的地方。

Where all the penguins are.

不是。

No.

不是那样的。

That's not it.

差不多，但还不对。

Not quite.

不过你已经很接近了。

Although you're not far off.

磁铁的两极是磁场最强的地方。

The poles of a magnet are where the magnetic field is strongest.

两极会排斥或吸引其他磁性物体。

The poles repel or attract other magnetic objects.

我们来测试一下，好吗

Let's test it out, shall

我们？

we?

是的。

Yeah.

对。

Yeah.

我们把这两根条形磁铁首尾相接推一下。

Let's push these two bar magnets end to end.

准备好了吗？

Ready?

我说，轻轻敲一下。

I say tap it.

你真的在推吗？

Are you even pushing next?

我真的在推。

I really am.

但感觉磁铁在往回推。

But it's like the magnet is pushing back.

彼此相互推开。

Pushing apart from each other.

像一种无形的力量。

Like an invisible power.

你一定是让两个南极或两个北极相对了。

You must must have two south poles or two north poles facing each other.

在这种情况下，磁铁会相互排斥，把对方推开。

In that case, the magnets will repel or push the other one away.

哎呀，别闹了。

Oh, come on.

我们力气很大的。

We're strong.

我们能做到。

We can do it.

我们再试一次。

Let's try again.

你会把自己困住的。

You'll just tie yourself out.

宇宙中没有任何力量能把磁铁的这两面推到一起。

No force in the universe could push these sides of a magnet together.

好吧。

Okay.

我们换种方式试试。

Let's try the other way.

你看到了吗？

Did you see that?

它们粘住了。

They stuck.

它自己会动。

It moves by itself.

磁场把它们拉到了一起。

The magnetic field pulled them together.

所以，如果磁场让磁铁具有磁性，那又是什么产生了磁场呢？

So if a magnetic field is what makes a magnet magnetic, what's making the magnetic field?

我们需要更仔细地观察它们的原子。

We'll need to take a closer look at their atoms.

它们非常小。

They're really small.

比细菌还要微小。

Tinier than bacteria.

它们太小了，即使使用显微镜也看不到。

They're way too tiny to see, even with a microscope.

那么，让我们戴上亚原子眼镜吧。

So let's use our subatomic spectacles.

那是什么？

What's that?

哦，只是我想象出来的东西。

Oh, just something I imagined up.

它们能帮我们看到原子层面的东西。

They'll help us see things on the atomic level.

我们先看什么？

What should we look at first?

我们先看看我桌上的这个金属回形针。

Let's check out this metal paper clip on my desk first.

准备进入量子世界。

Ready to go quantum.

我们以前从来没去过那里。

We've never gone there before.

戴上亚原子眼镜。

Subatomic spectacles on.

哇哦。

Woah.

哦，酷。

Oh, cool.

我能看到这里的是

I can see here's the

周围飞舞着微小的东西。

tiny little things buzzing around.

它们是原子。

They're atoms.

哇哦。

Woah.

到处都是原子。

There are atoms everywhere.

哇哦。

Woah.

太神奇了。

That's amazing.

你知道吗，我听说不能相信原子。

You know, I've heard you can't trust atoms.

为什么？

Why not?

因为它们构成了万物。

Because they make up everything.

是的。

Yes.

宇宙中的一切都是由原子构成的。

All the stuff in the universe is made of atoms.

一切吗？

Everything?

水母、房子、锅？

Jellyfish, houses, pots?

是的。

Yep.

一个回形针由数十亿甚至数万亿个原子组成，而每个原子又由更小的物质构成。

A paper clip is made of billions and trillions of atoms, and each atom is made of even smaller stuff.

即使是一个微小的东西，里面也包含着如此多更小的组成部分。

Even a tiny thing has so much other tiny things inside it.

那是什么声音？

What's that noise?

电子。

Electrons.

它们正在围绕构成这个回形针的所有原子高速运动。

They're whizzing around all the atoms that make up this paper clip.

电子。

Electrons.

我觉得那是无数微小的电荷。

I think it's lots of teeny bits of electricity.

我觉得它们在电线里？

And I think they're in power lines?

是的。

Yeah.

当它们在云中跳跃时，就变成了闪电。

When they jump around in clouds, they become lightning.

当它们流过电线时，就变成了电流。

And when they flow through wires, they become electricity.

对。

Yes.

电子产生电流，而且它们对于使磁铁具有磁性至关重要。

Electrons make electricity, and they are essential in making a magnet magnetic.

这需要大量的电子。

That's a lot of electrons.

它们移动得太快了，看起来只是一片模糊。

They move so fast they're just a blur.

所以它看起来像围绕原子的云。

So it looks like a cloud around the atom.

让我们放慢这些电子的速度，以便更好地观察它们。

Let's slow these electrons down so we can see them better.

嘿。

Hey.

你好。

Hi.

电子在说话。

The electrons are talking.

我在这里。

I'm here too.

她大概忘记我了。

Guess she forgot about me.

你觉得它们听起来有点悲伤吗？

Do they sound a bit sad to you?

别理他们。

Don't mind them.

电子总是消极的。

Electrons are always negative.

随便吧。

Whatever.

电子围绕原子运动，但它们从不会相互碰撞。

Electrons move around an atom, but they never bump into each other.

我们把这种运动称为自旋。

We call this movement spin.

这种特殊的自旋赋予了它们一种能力。

This special spin gives them a power.

那是什么？

What is it?

它会产生一个非常微小的磁场，使它们变成微型磁铁。

It creates a very tiny magnetic field, and it turns them into mini magnets.

电子因为是电荷而非常快速地围绕原子旋转。

The electrons are spinning around the atom very quickly because they're electricity.

我认为它们围绕原子旋转的原因是它们彼此不喜欢。

The reason they're spinning around it, I think, is because they don't like each other.

正确。

Correct.

谁在乎呢？

Who cares?

我喜欢有自己的空间。

I like my own space.

是的。

Yeah.

我更喜欢独自旋转。

I prefer to spin solo.

我也是。

Me too.

想象所有电子各自旋转，朝向各个不同的方向。

Picture all the electrons spinning on their own, going in lots of different directions.

每个电子都有一个磁场，但非常微弱。

They each have a magnetic field, but it's very weak.

现在让我们来看看那些磁铁中的原子

Now let's take a look at the atoms in those magnets of

我的。

mine.

哇哦。

Woah.

磁铁中的电子都在朝同一个方向旋转。

The electrons in the magnet are all spinning the same way.

它们没有四处散乱。

They're not trailing all over.

同步旋转。

Synchronized spinning.

我们还有更酷的

We have more cool

当我们一起旋转时。

when we spin together.

在磁铁中，电子都朝同一个方向排列，像团队一样一起旋转。

In magnets, the electrons all line up in the same direction and spin together like they're in a team.

团队合作让梦想成真。

Teamwork makes the dream work.

它们所有微小的磁场联合起来，形成一个强大的磁场。

All their mini magnetic fields join together to create one strong magnetic field.

它们变得更强了。

They get it stronger.

好的。

Okay.

你已经看到电子在回形针中如何单独运动，以及在磁铁中如何一起运动。

You've seen how electrons move by themselves in a paper clip and how they move together in the magnet.

现在让我们把它们互相介绍下。

Now let's introduce them to each other.

我们先调整一下眼镜设置。

Let's just adjust our spectacle settings.

好的。

Okay.

我能看见回形针里的电子。

I can see the electrons in the paperclip.

没有协调性。

No coordination.

等等。

Hang on.

有些变化正在发生。

Something's changing.

那边是什么？

What's over there?

我不知道，但是

I don't know, but

感觉我们都应该朝这个方向旋转。

it feels like we should all spin this way.

就像电子注意到了磁铁一样。

It's like the electrons have noticed the magnet.

它在把我拉过去。

It's pulling me in.

哇哦。

Woah.

电子都转向了磁铁。

The electrons are all turning towards the magnet.

它们都开始朝同一个方向旋转了。

And they're all starting to spin the same way.

哇哦。

Woah.

哇哦。

Woah.

磁铁的强磁场正在吸引电子的微小磁场，并将它们排列成一致的方向。

The strong magnetic field of the magnet is attracting the tiny magnetic fields of the electrons and pulling them into line.

这种感觉不一样。

This feels different.

它们已经开始朝同一个方向旋转了。

They've started spinning altogether in the same direction.

所以现在这个回形针被磁化了。

So now this paper clip is magnetized.

我们有磁性了。

We're magnetic.

回形针和磁铁粘在一起了。

The paper clip and the magnet are stuck together.

当然，当你移除磁场时就不是了。

Until you take away the magnetic field, of course.

我受够了。

I'm tired of this.

我要做自己的事。

I'm doing my own thing.

是的。

Yeah.

这挺酷的，但我想一个人待着了。

This is cool for a while, but I wanna be on my own now.

它们又朝不同方向去了。

They're going different ways again.

当我们移开磁铁时，回形针的电子又开始各自旋转了。

When we took away the magnet, the paper clip's electrons went back to spinning on their own.

一旦移开磁铁，这种效应就会消失。

The effect wears off after you take the magnet away.

所以你的玩具或冰箱贴可以保持磁性，但回形针只有在靠近强磁场时才会具有磁性。

So while your toys or fridge magnets will stay magnetic, a paper clip will only be magnetic if it's close to a strong magnetic field.

让我们摘下这些亚原子眼镜，把一切恢复到正常大小。

Let's take these subatomic spectacles off and get things back to regular size.

那真是太酷了。

That was so cool.

而且我们根本没离开你的办公室。

And we never even left your office.

是的。

Yeah.

真难以置信，有这么多事情在发生。

It's amazing how much stuff is going on.

但我们的眼睛看不到它们。

We just can't see it with our eyes.

等等，凯西。

But hang on, Kathy.

电子不是无处不在的吗？

Aren't electrons in everything?

是的。

Yes.

不过你不能用磁铁让这张纸里的电子排成一行，对吧？

You can't use a magnet to make the electrons in this piece of paper lineup though, can you?

或者这株植物？

Or this plant?

或者其他任何东西。

Or any other stuff.

比如我的狗。

Like my dog.

她叫豆子。

Her name's beans.

不行。

No.

这只能在铁、镍或钴等特殊金属上起作用。

This only works with special metals like iron, nickel, or cobalt.

这就是为什么纸张或塑料无法被磁化，或者大多数其他东西也不行。

That's why paper or plastic can't be made magnetic or really most other things.

抱歉，Beans。

Sorry, beans.

在你走之前，我能给你看看我最喜欢的磁铁吗？

Before you go, can I show you my favorite magnet?

好的。

Yeah.

跟着

Follow

我。

me.

凯西，你有没有想象过

Kathy, did you imagine

我们到南极洲去？

us down to Antarctica?

是的。

Yes.

我们到了南极。

We're at the South Pole.

还记得磁铁有两极吗？

Remember how magnets have poles?

北极和南极？

The North Pole and the South Pole?

地球之所以有这两个极，是因为地球本身就是一个巨大的磁铁。

Well, the Earth has both of those because the Earth is a giant magnet.

什么？

What?

还记得那些可以被磁化的金属吗？

Remember some of those metals that can be magnetic?

铁和镍？

Iron and nickel?

是的。

Yes.

在地球深处，地核外层由铁和镍组成。

Well, deep underground, the outer core of the planet is made of iron and nickel.

地球是金属做的？

The planet is made of metal?

并不是固态的金属。

It's not solid metal.

这些金属是高温液态的，并且在流动旋转。

These metals are hot and liquid, swirling around.

这使得它像磁铁一样发挥作用。

Which makes it act like a magnet.

对。

Correct.

很强。

Strong.

它不会让你的磁铁粘在地上。

It won't make your magnet stick to the ground.

但它能让指南针找到北方，甚至保护地球免受太阳的侵害。

But it's how compasses find north and even protects the planet from the sun.

为什么？

How?

我们可能得留到另一天再讲了。

We might have to save that for another day.

是的。

Yeah.

我感觉很冷，这只企鹅一直给我送鱼。

I'm pretty cold, and this penguin keeps bringing me fish.

它喜欢你。

He likes you.

嗯，

Well,

我得回实验室了。

it's back to the lab for me.

谢谢你教我们关于磁铁的知识，凯西。

Thanks for teaching us about magnets, Kathy.

再见，凯西。

Bye, Kathy.

所以，奥利、弗雷德、吉米、索菲、亨利、奥斯卡和基拉，磁铁之所以起作用，是因为它们具有看不见的磁场。

So, Ollie, Fred, Jimmy, Sophie, Henry, Oscar, and Keira, magnets work because they have invisible magnetic fields.

不是像足球场那样的场。

Not like a football field.

这是磁铁吸引或排斥其他磁铁的空间。

It's the space where magnets pull or push on other magnets.

它会吸引

It attracts

或排斥。

or repels.

磁场来自电子，电子是围绕原子旋转的微小粒子。

Magnetic fields come from electrons, tiny particles that spin around in atoms.

在大多数物体中，电子以随机方向旋转。

In most objects, electrons spin in random directions.

每个电子都像一个微型磁铁，但它的磁性非常弱。

Each one is like a mini magnet, but it's really weak.

不是磁铁的东西。

Stuff that's not a magnet.

比如塑料或者网球。

Like plastic Or a tennis ball.

或者豆子。

Or beans.

但在磁铁中，电子会排列整齐并朝同一方向旋转。

But in magnets, the electrons line up and spin the same way.

它们产生吸引力。

They're drawing forces.