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. 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 length of its body.
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外研版九上《Module 11 Unit 2 It was a quiet country village》word教案
外研版九上《Module 3 Unit 3 Language in use》word导学案
外研版九上《Module 6 Save our world》(Unit 3)word教案
外研版九上《Module 3 Unit 2 Liu Xiang was trained for gold》word导学案
外研版九上《Module 5 Unit 3 language in use》word教案
外研版九上《Module 11 Population》word教案
外研版九上《Module 7 Australia》word教案和练习
外研版九上《Module 4 Great inventions》word重难点辅导
外研版九上《Module 6 Save our world》word同步教案
外研版九上《Module 6 Save our world Unit 3 Language in use》word导学案
外研版九上《Module 6 Unit 1 It’s wasteful to throw away paper and metal》word导学案
外研版九上《Module 11 Population》word同步教案
外研版九上《Module 7 Australia Unit 3 Language in use》word导学案
外研版九上《Module 11 Unit 1 It’s the biggest city in China》word学案
外研版九上《Module 11 Unit 3 Language in use》word导学案
外研版九上《Module 4 Great inventions》(Unit 3)word导学案
外研版九上《Module 11 Population》word全模块教案
外研版九上《Module 11 Unit 2 It was a quiet country village》word导学案
外研版九上《Module 6 Unit 1 It’s wasteful to throw away paper and metal》word预习导学案
外研版九上《Module 11 Unit 3 Language in use》word教案
外研版九上《Module 11 Population》word重难点辅导
外研版九上《Module 4 Great inventions》word全模块教案
外研版九上《Module 12 Summer in LA》word全模块教案
外研版九上《Module 3 Sporting life》word教学参考
外研版九上《Module 3 Sporting life》word学案
外研版九上《Module 6 Save our world》word教学参考
外研版九上《Module 11 Unit 1 It’s the biggest city in China》word教案
外研版九上《Module 3 Unit 1 When will the match be held》word学案
外研版九上《Module 5 Unit 2 There’s no shouting and no running》word导学案
外研版九上《Module 3 Sporting life》word同步教案