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Salt vs. Ice
食鹽大戰冰塊
Y: Why does salt melt ice?
為什麼食鹽能讓冰塊融化?
D: It lowers the melting and freezing point of water.
是因為食鹽將水的熔點和冰點降低了。
Y: Oh,,I don't get it. Doesn't that mean the salt make ice colder?
等一下，我不明白。這就意味著食鹽讓冰的溫度變得更低嗎?
D: Let me water freezes at thirty-two degrees Fahrenheit,right? At that temperature we can say that the rate of freezing is the same as the rate of melting.
我解釋一下。純淨水的冰點是32華氏度，對吧?這個溫度既是冰點也是熔點。
Y: So in other words, at water's freezing point there's a sort of equilibrium between freezing and melting.
也就是說，水的冰點就是結冰和融化的平衡。
D: wing salt on ice upsets the balance.
是的。在冰上灑鹽擾亂了這種平衡。
Y: Upsets it how?
怎麼打亂的呢?
D: The salt dissolves into the liquid water, which means that some of the water molecules are replaced by salt. Since there are now fewer liquid water molecules to be captured and frozen by the ice, the rate of freezing drops.
鹽溶解在水中，就是說一部分水分子被鹽取代了。既然結冰的液態水分子減少了，冰點自然降低了。
Y: I think I get Since the rate of melting stays the same, there's more melting going on than freezing. And so the ice melts.
我明白了。水的熔點不變，融化的水分子比結冰的多，所以冰塊就融化了。
D: Right.
對。
Y: Interesting.
很有趣。
D: In fact, anything that dissolves in water will do the trick. You could pour sugar on ice and it willmelt. But I guess since salt is cheaper it's used more often.
其實，任何溶於水的物質都可以使冰融化。把糖灑在冰上，冰也會融化。但是我想也許由於鹽比較便宜，所以經常被使用。
part 2The Biggest Magnet
最大的磁體
A: What's the biggest magnet ever?
究竟什麼是最大的磁體?
B: Well, that's a great question. Well, for starters you'd have to mention whoppers like the hybrid magnet at the National High Magnetic Field Lab in Tallahassee, magnet weighs thirty-four tons and stands twenty-two feet t magnets in hospitals, physics labs, and other facilities help in cutting edge research. However, even a magnet the size of a building can't compete with a magnet the size of a planet.
嗯，問得好。對於初學者來說，不得不提一下那些龐然大物，比如佛羅里達塔拉哈西的國家高磁場實驗室的混合磁體。這塊磁鐵重34噸，立起來有22英尺高。醫院，物理實驗室和其他裝置裡的'巨型磁體對尖端研究有幫助。然而，即使是一塊建築物大小的磁體也不能和一塊行星大小的磁體相匹敵。
A: A magnet the size of a planet?
一塊行星大小的磁體?
B: The Earth itself is a magnet! Researchers think it's the effect of convection currents in our planet's molten interior that causes the entire Earth to behave as one gigantic magnet, with a North and South ever you look at a compass, what you're doing is reading the magnetic field of the planet on which you are standing.
地球本身就是一塊磁體。研究者們認為，是地球內部熔岩裡對流流的作用使得整個地球像個擁有南北磁極的巨型磁體一樣運轉。每當你看著指南針的時候，你所做的就是讀取你所在行星的磁場。
A: So that must be the biggest magnet than anywhere.
所以那就是最大的磁體咯。
B: Yet, even a magnet the size of a planet can't compete with a magnet the size of a star.
但是，即使是行星大小的磁體也不能和恆星大小的磁體相匹敵。
A: A star?
恆星?
B: what about the sun? The sun is a magnet. In this case, the magnetic field is probably generated by swirling plasma. Magnetic storms on the sun are powerful enough to have an effect on satellites and communication systems all the way here on Earth.
比如說太陽?太陽是一塊磁體。假若這樣，磁場可能是由旋動的等離子產生的。太陽上的磁暴威力足夠強大，可以對人造衛星和地球上通訊系統的各個方面產生影響。
A: So is that?
那就是最大的了?
B: Not even close. There are things in space that put all of these magnets to shame.
還差得遠呢。宇宙中還有更多讓這些磁體相形見絀的事物呢。
A: Super magnet in space? What are they?
宇宙中的超強磁體?是些什麼呢?
B: Next time.
下次再說吧。
