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 millions 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 cells 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 cells are linked together, the effects can be astonishing.
The electric eel is an amazing storage battery. It can send a jolt of as much as eight hundred volts of electricity through the water in which it lives. As many as four-fifths of all the cells in the electric eels body are specialized for generating electricity, and the strength of the shock it can deliver corresponds roughly to the length of its body.
Mind the gap:伦敦地铁提示音背后的温暖爱情故事
公路救赎: 拥堵让中国人重拾自行车
国际英语资讯:2 Palestinians killed in Gaza explosion
女性面临新的保健深坑!
体坛英语资讯:China trounce Germany 3-1 and one step away from 2020 Olympic womens volleyball game
体坛英语资讯:Striker Benedetto says goodbye to Boca ahead of Marseille move
萌宝宝趣表情:我哥哥唱歌实在太难听!
3D打印枪支势不可挡 如何应对成难题
写给20多岁的你:该和这些幼稚行为说拜拜啦!
稀世蓝钻以960万美元拍卖价刷新世界纪录
国际英语资讯:Bangladesh poverty rate falls by 50 pct in 10 years: foreign minister
改变自己才最重要:10种简单方法建立自信
体坛英语资讯:CSL Roundup: Guoan beat Hebei 2-0 to keep CSL title hope alive, Renhe deep in relegation tro
国际英语资讯:Turkey receives 2nd batch of S-400 defense system from Russia
义务与责任: 中国科学家率先查明H7N9病毒来源
你真的会经营感情吗?警惕10个坏习惯毁了爱情
瞅准时机: eBay小步快跑杀回中国
国际英语资讯:Indonesia to start constructing new capital next year
关于我们的大脑你所不知道的五件事
校园集结号: 史上最难就业年恐已来临