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[煎蛋小學堂]如何讓磁鐵消磁?

作者:admin

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2015-7-8 13:30

[煎蛋小學堂]如何讓磁鐵消磁?

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[煎蛋小學堂]如何讓磁鐵消磁?

節目簡介:

你是不是對日常生活中一些稀松平常的現象產生過好奇心?

到底為什么會是醬紫的呢?

科普類視頻節目《煎蛋小學堂》幾分鐘為讓你茅塞頓開,雙語文本+視頻+MP3更是不容錯過的英語口語、口譯好素材呢~~

還在等什么,一起來一場對未知世界的奇妙探索之旅吧~~

參考雙語文本:

This is a neodymium magnet-it's pretty darn strong.And now,after heating it in a flame...it's no longer magnetic.Well,to build a magnet,all you need to do is find a bunch of magnetic atoms .
這是一上釹磁鐵,它磁性很強,現在在火焰炙烤后它沒有磁性了,想要做磁鐵,你先得找到一些磁性的原子。

That's easy-they're the ones with half-filled electron shells in the middle of any of the major blocks of the periodic table, and then make a compound where the magnetic fields of the atoms align in the same direction this is Ferromagnetism, named after Iron,which is pretty darn magnetic.
這簡單,它們就是那些外層電子半滿的原子,在元素周期表中主塊中間的位置,然后合成原子的磁場方向都相同的化合物,這是磁鐵,以鐵命名,磁性較強。


(http://v.youku.com/v_show/id_XNjE1NDU0MTQ4.html)


However,it's not always so easy.Sometimes the atoms actually want to align their magnetic fields in alternating directions.This is called "anti-ferromagnetism,"and it means the bulk material won't have a magnetic field at all.Or,sometimes the tendency of the atomic magnets to align (or anti-align)is just too weak to overcome their intrinsic jiggling.
但是事情沒這么簡單,有時原子的磁場方向肢相互交替,這種被稱為“抗鐵磁性“這就意味著這塊材料不產生磁場或者有時原子磁場相互對擠(或交替對擠)的趨勢太弱,無法克服其本身的震動。

That is,their temperature!In which case,even though all the individual atoms in the material are magnetic,the material as a whole isn't.However,in a strong external magnetic field,the atoms do tend to align with each other in the direction parallel to the field.This is called "para-magnetism,"and liquid oxygen is a great example:it's attracted by a magnet,though it doesn't stay magnetized afterwards.
也就是溫度!此時即使材料內部所有原子都具有磁性,整塊材料卻沒有 但是 在外部強磁場內,原子會沿平行于外部場的方向相互對齊,這就是順磁性,液氧就是個好例子,它會被磁鐵吸引,但之后并不會保持磁性。

But let's get back to the question-how do you destroy a magnet?Well,a material can only be ferromagnetic it its temperature is low enough:above a certain point,the nicely ordered atomic magnetic fields"melt"into disorder,just as ice crystals melt into water when heated past zero celsius. So to destroy a manget,you just need to heat it up past its "magnetic melting point",called the "Curie Temperature"it probably won't look like much is happening,but once the atoms are jiggling around enough,their magnetic fields will no longer all point in the same direction.
那么,回到開始的問題。怎么去持物體的磁性?材料僅能在溫度足夠低時表現出磁性,超過某一點是整齊排布的原子磁場會“熔“成一片混亂,正如冰在加熱至零攝氏度以上會化成水,想要去掉磁鐵磁性,你得將物體加熱,超過其“磁性轉變點“,又稱“居里點“看上去似乎什么也沒發生。但當原子振動足夠劇烈時,它們磁場將不再都指向相同的方向。

Magnet destroyed!And just as different elements melt from solid to liquid at different temperatures,They also melt from being ferromagnetic to paramagnetic at different temperatures,which you can explore in this sweet interactive periodic table.Which also plays all of the Periodic Table of Videos.
沒有磁性啦!正如不同的材料熔點不同,它們的磁性轉變點的溫度也不同,你可以在這個動態元素周期表中試試看,那里還有所有元素周期表視頻。

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