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电子管这个名詞,对許多人可能是陌生的。但是如果提起“真空管”或者是收音机里面的“灯泡”来,那又是人人都知道的了。因为一般的电子管里面都是真空的,所以人們習慣把它叫做“真空管”。但是也有一部分电子管內是含有气体的,因此,过去常用的“真空管”这个名称就不能滿足电子管的全部含义了。所以我们还是应該把它們总称为电子管。在二十世紀剛开始的十年中,人們已經会利用有线的电話和电报来傳遞消息了。不論电話或电报,都是把消息首先变成电的訊号,譬如电話中話筒的作用就是把人說話的声波(空气的振动)变为相应的电流的振动。这种振动的电流通过收听者的耳机的时候,又被轉变为膜片的振动而發出說話的声音来。一个人講話的声音是不可能傳得很远的。但是如果把这种声音变成电的訊号,就可能靠电綫輸送到較远的地
The term electronic tube may be unfamiliar to many people. But if you mention the “vacuum tube” or the “bulb” on the radio, then everyone knows it. Because the general electron tube is vacuum inside, people are used to calling it “vacuum tube”. However, some of the electron tubes contain gas. Therefore, the name “vacuum tube” commonly used in the past cannot satisfy the full meaning of the electron tube. So we should still call them tubes. In the first decade of the twentieth century, people already used wired telephones and telegrams to deliver news. Whether telephones or telegrams are signals that turn messages into electricity first. For example, the function of a microphone in a telephone call is to change the sound wave (the vibration of air) of a person’s speech into the vibration of the corresponding current. When this vibrating current passes through the listener’s earphone, it is transformed into diaphragm vibration and speaks. The voice of a person speaking cannot be transmitted very far. However, if this sound is converted into an electrical signal, it may be transported by wires to a remote location.