There are several fundamental forces that hold our universe together.
One of these, of course, is gravity, the force between objects that have mass.
Another important force is the electromagnetic force.
The electromagnetic force is responsible for chemical reactions.
譯文：有幾種基本力將我們的宇宙維系在一起吸重。其中之一互拾，當(dāng)然，是重力嚎幸，存在于有質(zhì)量的物體之間的力颜矿。另一個(gè)重要的力是電磁力。電磁力是產(chǎn)生化學(xué)反應(yīng)的原因嫉晶。
Without it, there would be no atoms or molecules.
Up until a couple of hundred years ago, very little was known about this force.
Learning about the electromagnetic force and how to use it was a major step forward.
It revolutionized communication, transportation and manufacturing.
Imagine what life would be like without electricity!
譯文：沒(méi)有電磁力骑疆，就沒(méi)有原子或分子。直到幾百年前替废，人們對(duì)這種力量知之甚少封断。學(xué)習(xí)電磁力以及如何使用它是向前邁進(jìn)的重要一步。它徹底改變了通訊舶担、運(yùn)輸和制造業(yè)坡疼。想象一下沒(méi)有電的生活會(huì)是什么樣子！
Question:
— Which of the fundamental forces is between objects that have mass?
— Gravity
Put the sentences below in order:
(1) One of these, of course, is gravity, the force between objects that have mass.
(2) The electromagnetic force is responsible for chemical reactions.
(3) Another important force is the electromagnetic force.
(4) There are several fundamental forces that hold our universe together.
Correct Order: (4) (1) (3) (2)
The electromagnetic force has two parts, the electric force and the magnetic force.
The electric force is the force between electrically charged particles such as electrons and protons.
Electric charges attract or repel each other with a force that depends on the distance between them.
The magnetic force is the force between magnetic poles, such as the north and south pole.
譯文：電磁力有兩部分衣陶，電力和磁力柄瑰。電力是帶電粒子(如電子和質(zhì)子)之間的作用力。電荷相互吸引或排斥剪况，其作用力取決于它們之間的距離教沾。磁力是磁極之間的力，如北極和南極译断。
In fact, the Earth is like a large bar magnet, with a north and a south pole.
Many animals use the Earth's magnetic field to navigate during their migrations.
We can also see this magnetic field when we use a compass.
譯文：事實(shí)上授翻，地球就像一個(gè)巨大的有北極和南極的條形磁鐵。許多動(dòng)物在遷徙過(guò)程中利用地球磁場(chǎng)導(dǎo)航孙咪。當(dāng)我們使用指南針時(shí)堪唐，我們也能看到這個(gè)磁場(chǎng)。
Questions:
1.— For what purpose do many animals use the Earth's magnetic field?
? — for navigation
2.— Electrons and protons are examples of what?
? — electrically charged particles
Repeat & Read Sentences:
1. Imagine what life would be like without electricity!
2. In fact, the Earth is like a large barmagnet, with a north and a south pole.
3. There are several fundamental forces that hold our universe together.
4. The magnetic force is the force between magnetic poles, such as the north and south pole.
Why does the Earth have a magnetic field?
Many scientists believe that the Earth's magnetic field is due to the Earth's rotation.
Deep inside the Earth is a solid iron core, surrounded by a liquid metal outer core.
The moving electric currents inside this liquid metal create a magnetic field.
譯文：為什么地球有磁場(chǎng)?許多科學(xué)家認(rèn)為地球的磁場(chǎng)是由地球的自轉(zhuǎn)引起的翎蹈。在地球的深處是一個(gè)固體鐵核淮菠，被液態(tài)金屬的外核所包圍。液態(tài)金屬內(nèi)部流動(dòng)的電流產(chǎn)生了磁場(chǎng)荤堪。
Question:
— What's deep inside the Earth?
— a solid iron core
The Earth's magnetic field is important because it protects us from the solar wind.
The solar wind is a current of charged particles coming at us from the Sun.
When the solar wind nears the Earth, the Earth's magnetic field deflects it away.
This protects the Earth from the radiation, which can be dangerous to life.
It also protects the satellites that we use for communication.
譯文：地球的磁場(chǎng)很重要合陵，因?yàn)樗鼙Ｗo(hù)我們免受太陽(yáng)風(fēng)的影響。太陽(yáng)風(fēng)是來(lái)自太陽(yáng)的帶電粒子電流澄阳。當(dāng)太陽(yáng)風(fēng)接近地球時(shí)拥知，地球的磁場(chǎng)就會(huì)使其偏離。這可以保護(hù)地球免受可能危及生命的輻射碎赢。它也可以保護(hù)我們用來(lái)通訊的衛(wèi)星低剔。
Exercises:
1.— What protects the Earth from the solar wind?
? — The Earth's magnetic field
2. When the solar wind nears the Earth, the Earth's magnetic field deflects it away. This protects the Earth from the radiation, which can be dangerous to life.
Repeat & Read Sentences:
1. The Earth's magnetic field is important because it protects us from the solar wind.
2. The Earth's magnetic field protects the Earth from the solar wind.
3. Many scientists believe that the Earth's magnetic field is due to the Earth's rotation.
4. When the solar wind nears the Earth, the Earth's magnetic field deflects it away.
