Circuits — series, parallel and potential dividers · 电路——串联、并联与分压器
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| components/kəmˈpəʊnənts/ | 元件 | yuán jiàn |
| series/ˈsɪəriːz/ | 串联 | chuàn lián |
| parallel/ˈpærəlel/ | 并联 | bìng lián |
| potential divider/pəˈtenʃl dɪˈvaɪdə/ | 分压器 | fēn yā qì |
| fuse/fjuːz/ | 保险丝 | bǎo xiǎn sī |
| thermistor/ˈθɜːmɪstə/ | 热敏电阻 | rè mǐn diàn zǔ |
| LDR/ˌel diː ˈɑː/ | 光敏电阻 | guāng mǐn diàn zǔ |
Building circuits
- Real gadgets are circuits built from a handful of components 元件, wired in two basic ways.
- Get the rules for series 串联 and parallel 并联 and you can predict any simple circuit.
- We finish with a clever trick: the potential divider 分压器.
搭建电路
- 真实的小装置是由少数几个元件搭建的电路,以两种基本方式接线。
- 掌握串联和并联的规则,你就能预测任何简单电路。
- 我们以一个聪明的把戏结束:分压器(potential divider)。
Components to know
- cell / battery — drives the current; a switch breaks or completes the circuit.
- resistor (fixed) and variable resistor (to control the current).
- fuse 保险丝 — melts if the current is too big; diode / LED — current one way only (an LED also lights).
- thermistor 热敏电阻 — resistance falls as it gets hotter; LDR 光敏电阻 — resistance falls as light gets brighter.
Standard circuit symbols
要知道的元件
- 电池——驱动电流;一个开关断开或完成电路。
- 电阻器(固定)和可变电阻器(控制电流)。
- 保险丝(fuse)——如果电流太大就熔断;二极管 / LED——电流只单向(一个 LED 还会亮)。
- 热敏电阻(thermistor)——电阻随它变热而下降;光敏电阻(LDR)——电阻随光变更亮而下降。
标准电路符号
Build the current with Ohm's law · 用欧姆定律建立电流
Turn up the voltage and the electrons speed up and the bulb glows brighter; add resistance and the current drops. I = V/R, brightness = power. · 调高电压,电子加速,灯泡发光更亮;加电阻,电流下降。I = V/R,亮度 = 功率。
What happens to the resistance of a thermistor as it gets hotter? · 一个热敏电阻的电阻随它变热会怎样?
A thermistor's resistance falls as temperature rises — useful in temperature-sensing circuits. · 一个热敏电阻的电阻随温度上升而下降——在温度感应电路中有用。
Match each circuit rule to where it applies. · 把每个电路规则与它适用之处配对。
Each item links the term to its correct meaning. · 每一项把术语与它正确的含义联系。
Series circuits
- The parts form one single loop.
- The current is the same at every point.
- The supply p.d. is shared between the components.
- Resistors in series add up: $R_{\text{total}} = R_1 + R_2 + \dots$
Series and parallel circuits
串联电路
- 各部分形成一个单一的回路。
- 电流在每一点都相同。
- 供电 p.d. 在元件之间被分享。
- 串联的电阻器加起来:$R_{\text{total}} = R_1 + R_2 + \dots$
串联和并联电路
A $3.0\ \Omega$ and a $5.0\ \Omega$ resistor are connected in series. What is the total resistance, in Ω? · 一个 $3.0\ \Omega$ 和一个 $5.0\ \Omega$ 的电阻器被串联连接。总电阻是多少,以 Ω 计?
In series, resistances add: $R = 3.0 + 5.0 = 8.0\ \Omega$. · 串联时,电阻相加:$R = 3.0 + 5.0 = 8.0\ \Omega$。
In a series circuit, the current is: · 在一个串联电路中,电流是:
There is only one path, so the same current flows through every component in a series circuit. · 只有一条路径,所以相同的电流流过一个串联电路中的每个元件。
Parallel circuits
- The parts are on separate branches.
- Each branch gets the full supply p.d.; the current splits between branches.
- The total resistance is less than the smallest single resistor: $\dfrac{1}{R_{\text{total}}} = \dfrac{1}{R_1} + \dfrac{1}{R_2}$
- Home lamps are wired in parallel — each gets full voltage, and one failing leaves the others on.
并联电路
- 各部分在分开的分支上。
- 每个分支得到完整的供电 p.d.;电流在分支之间分裂。
- 总电阻小于最小的单个电阻器:$\dfrac{1}{R_{\text{total}}} = \dfrac{1}{R_1} + \dfrac{1}{R_2}$
- 家里的灯被并联接线——每个得到完整电压,而一个失效让其他的保持亮。
A $6.0\ \Omega$ and a $3.0\ \Omega$ resistor are connected in parallel. What is the total resistance, in Ω? · 一个 $6.0\ \Omega$ 和一个 $3.0\ \Omega$ 的电阻器被并联连接。总电阻是多少,以 Ω 计?
$\dfrac{1}{R} = \dfrac{1}{6.0} + \dfrac{1}{3.0} = \dfrac{1}{6} + \dfrac{2}{6} = \dfrac{3}{6}$, so $R = 2.0\ \Omega$ — less than the smallest resistor. · $\dfrac{1}{R} = \dfrac{1}{6.0} + \dfrac{1}{3.0} = \dfrac{1}{6} + \dfrac{2}{6} = \dfrac{3}{6}$,所以 $R = 2.0\ \Omega$——小于最小的电阻器。
Why are the lamps in a house wired in parallel? · 为什么一个房子里的灯被并联接线?
In parallel each lamp gets the full supply p.d., and a break in one branch does not stop the others. · 并联时每盏灯得到完整的供电 p.d.,而一个分支中的断开不会停止其他的。
Potential dividers
- Two resistors in series share the supply voltage — a potential divider.
- The bigger resistor takes the bigger share of the voltage:
- Use a thermistor or LDR as one resistor and the output voltage changes with temperature or light — perfect for switching a heater or lamp on automatically.
分压器
- 两个串联的电阻器分享供电电压——一个分压器。
- 更大的电阻器取电压的更大份额:
- 用一个热敏电阻或 LDR 作为一个电阻器,输出电压就随温度或光变化——非常适合自动打开一个加热器或灯。
Two equal resistors are in series across a $12\ \text{V}$ supply. What is the p.d. across one of them, in V? · 两个相等的电阻器跨过一个 $12\ \text{V}$ 供电串联。跨过它们之一的 p.d. 是多少,以 V 计?
Equal resistors share the voltage equally: each gets $\dfrac{12}{2} = 6\ \text{V}$. · 相等的电阻器平等地分享电压:每个得到 $\dfrac{12}{2} = 6\ \text{V}$。
You've got it
- series: one loop, same current everywhere, p.d. shared, $R_{\text{total}} = R_1 + R_2$
- parallel: branches, each gets full p.d., current splits, $\dfrac{1}{R_{\text{total}}} = \dfrac{1}{R_1} + \dfrac{1}{R_2}$
- thermistor: R falls when hot · LDR: R falls in bright light
- potential divider: two series resistors share the voltage by their ratio
你掌握了
- 串联:一个回路,处处相同电流,p.d. 被分享,$R_{\text{total}} = R_1 + R_2$
- 并联:分支,每个得到完整 p.d.,电流分裂,$\dfrac{1}{R_{\text{total}}} = \dfrac{1}{R_1} + \dfrac{1}{R_2}$
- 热敏电阻:R 在热时下降 · LDR:R 在亮光中下降
- 分压器:两个串联电阻器按它们的比率分享电压