March 2017
Intermediate to advanced
232 pages
4h 44m
Chinese
Content preview from 自造手冊：新工業革命實務指南
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電路與元件
141
DCV 插槽。請把控制旋鈕轉到合適的直
流電壓檔位；您所要量測的電壓一定要
低於三用電表上所標示的數值。
例如，如果要測量大約 7 伏特的東西，
請把旋鈕設為 10 或 20 伏特。如果不確
定的話，請由數字最大的開始，一路往
下調。要量測電路兩點之間電壓的話，
只要用探針去觸碰所要量測電路該處外
露的導體（外露的電線或元件腳位都可
以），如
圖 15-32
。
交流電 / 直流電
您需要確定所要量測的電壓是
交流或直流。在量測交流電
時，探針電線要改插在三用電
表的專用插槽，而且大部分您
會遇到的
AC 電壓都可能危及
生命。如果搞錯的話，可能會
讓您的三用電表（更別說您的
身體了）嚴重受損。
圖 15-32
如何量測電阻兩端的電壓
您 也 可 以 量 測 流 經 某 段 電 路 的 電 流 大
小。與量測電壓相同，請將控制旋鈕設
定在適合您所要量測電流的檔位。與電
壓不同，您得把電路在想要量測的地方
「截斷」，並將探針放在截斷處，如
圖 15-
33
。
三用電表上所標示的數值就是流經電路
該處的電流大小。
圖 15-33
如何量測流過某個電阻的電流大小
歐姆定律
您用於電路中的許多元件只有在電壓正
確的情況下才會運作。繼續拿電壓與水
壓的相似性來打比方，這有點像是去推
動磨坊的水輪。如果把磨輪放在尼加拉
瓜大瀑布下面的話，它馬上就會被摧毀，
因為水壓實在是太強了。但如果用廚房
水龍頭的水流來轉動磨輪的話，當然完
全不會動。
電流、電壓與電阻並非彼此獨立的物理
量，如先前所述，它們是由歐姆定律彼
此相連：
V = R * I
第 15 章 電子與仙 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.