Electricity

The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in flickering candlelight, cars hesitate in the streets because there are no traffic lights to guide them, and food spoils in silent refrigerators.

Yet, people began to understand how electricity works only a little more than two centuries ago. Nature has apparently been experimenting in this field for million of years. Scientists are discovering more and more that the living world may hold many interesting secrets of electricity that could benefit humanity.

All living cell send out tiny pulses of electricity. As the heart beats, it sends out pulses of record; they form an electrocardiogram, which a doctor can study to determine how well the heart is working. The brain, too, sends out brain waves of electricity, which can be recorded in an electroencephalogram. The electric currents generated by most living cells are extremely small - often so small that sensitive instruments are needed to record them. But in some animals, certain muscle cells have become so specialized as electrical generators that they do not work as muscle cells at all. When large numbers of these cell are linked together, the effects can be astonishing.

The electric eel is an amazing storage battery. It can seed a jolt of as much as eight hundred volts of electricity through the water in which it live. ( An electric house current is only one hundred twenty volts.) As many as four-fifths of all the cells in the electric eel’s body are specialized for generating electricity, and the strength of the shock it can deliver corresponds roughly to length of its body.

 

電

 

現(xiàn)代是一個(gè)電力時(shí)代。人們對電燈、收音機(jī)、電視和電話如此習(xí)慣，以至于很難想象沒有它們生活會(huì)是什么樣子。當(dāng)停電時(shí)，人們在搖曳的燭光中摸索著，汽車在街道上猶豫，因?yàn)闆]有紅綠燈來引導(dǎo)他們，而無聲冰箱里的食物會(huì)變質(zhì)。

 

然而，人們僅僅在兩個(gè)多世紀(jì)以前就開始了解電的使用原理了。顯然，大自然已經(jīng)在這個(gè)領(lǐng)域進(jìn)行了數(shù)百萬年的試驗(yàn)。科學(xué)家們越來越多地發(fā)現(xiàn)，生活世界可能包含許多有益于人類的電能的有趣秘密。

 

所有活細(xì)胞都發(fā)出微小的電脈沖。當(dāng)心臟跳動(dòng)時(shí)，它發(fā)出記錄的脈沖，形成心電圖，醫(yī)生可以研究心臟的運(yùn)作情況。大腦也發(fā)出電能的腦電波，可以在腦電圖中記錄下來。大多數(shù)活細(xì)胞所產(chǎn)生的電流非常小——通常很小，需要靈敏的儀器來記錄它們。但是在某些動(dòng)物身上，某些肌肉細(xì)胞變得像發(fā)電機(jī)那樣專業(yè)，以至于它們根本就不起肌肉細(xì)胞的作用。當(dāng)大量的這些細(xì)胞連接在一起時(shí)，效果會(huì)令人吃驚。

 

電鰻是一種神奇的蓄電池。它可以通過它所生活的水產(chǎn)生多達(dá)八百伏的電力。（電流只有一百二十伏特），電鰻體內(nèi)的所有細(xì)胞中有五分之四是專門用來發(fā)電的，而且電擊所產(chǎn)生的震動(dòng)強(qiáng)度與身體的長度大致相當(dāng)。