Electric Current · 电流
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| current/ˈkʌrənt/ | 电流 | diàn liú |
| ampere/ˈæmpeə/ | 安培 | ān péi |
A river of charge, counted by the second
- Switch on a lamp and charge starts flowing through the wire like water in a pipe.
- Current 电流 measures how much charge flows past a point each second.
- The more charge per second, the bigger the current and the brighter the lamp.
- It is the first quantity you need to understand any circuit.
一条电荷之河,按秒计数
- 打开一盏灯,电荷就像管道里的水一样开始在导线中流动。
- 电流量度每秒有多少电荷流过某一点。
- 每秒的电荷越多,电流越大,灯越亮。
- 它是理解任何电路所需的第一个量。
Current is charge per second
- Current is the rate of flow of charge: $I = \dfrac{Q}{t}$.
- Its unit is the ampere 安培 ($1\ \text{A} = 1\ \tfrac{\text{C}}{\text{s}}$).
- A $2\ \text{A}$ current means $2$ coulombs of charge pass each point every second.
- Current needs a complete path to flow — a break stops it instantly.
电流是每秒的电荷
- 电流是电荷的流动速率:$I = \dfrac{Q}{t}$。
- 它的单位是安培($1\ \text{A} = 1\ \tfrac{\text{C}}{\text{s}}$)。
- $2\ \text{A}$ 的电流意味着每秒有 $2$ 库仑的电荷流过每一点。
- 电流需要一条完整的路径才能流动——断开就立刻停止。
Build a current loop · 构建电流回路
Close a simple circuit and see current flow around the complete loop. · 闭合简单电路，观察电流在整个回路中流动。
$6\ \text{C}$ of charge flows past a point in $3\ \text{s}$. What is the current, in amperes? · $6\ \text{C}$电荷在$3\ \text{s}$内流过某点。电流是多少安培？
$I = Q/t = 6/3 = 2\ \text{A}$.
Electric current is defined as: · 电流的定义为：
$I = Q/t$ — charge flowing per second. · $I = Q/t$ — 每秒流过的电荷。
Current is measured in ____. · 电流以____为单位测量。
$1\ \text{A} = 1\ \tfrac{\text{C}}{\text{s}}$.
Conventional current vs electron flow
- By convention, current flows from + to − (the direction a positive charge would move).
- But in a metal wire it is really electrons that drift, from − to +.
- Both descriptions give the same circuit behaviour; we draw the conventional direction.
- So "current out of the + terminal" is the standard, even though electrons go the other way.
常规电流 vs 电子流
- 按约定,电流从 + 流向 −(正电荷会移动的方向)。
- 但在金属导线里,真正漂移的是电子,从 − 到 +。
- 两种描述给出相同的电路行为;我们画的是常规方向。
- 所以"电流从 + 端流出"是标准说法,尽管电子走的是反方向。
In which direction does conventional current flow? · 常规电流流向哪个方向？
Conventional current flows + → −, the way a positive charge would move. · 常规电流从+流向−，即正电荷移动的方向。
In a metal wire, the electrons actually drift opposite to the conventional current. · 在金属导线中，电子实际漂移方向与常规电流相反。
Electrons drift − → +, opposite to the conventional (+ → −) current direction. · 电子从−漂向+，与常规（+→−）电流方向相反。
What drives it
- A battery provides the push (a voltage) that keeps charge moving around the loop.
- Without a voltage difference, charges have no reason to flow — no current.
- The current is the same all the way around a simple (single-loop) circuit.
- Charge isn't used up as it goes; it just carries energy from the battery to the components.
是什么驱动它
- 电池提供推力(一个电压),让电荷绕着回路持续运动。
- 没有电压差,电荷就没有理由流动——没有电流。
- 在简单的(单回路)电路中,电流处处相同。
- 电荷在流动中不被用掉;它只是把能量从电池带到元件。
Select all · 所有 true statements about electric current. · 选择所有关于电流的正确陈述。
Current needs a loop, equals $Q/t$, and is driven by voltage. Charge carries energy but is not used up. · 电流需要回路，等于$Q/t$，并由电压驱动。电荷携带能量但不会被消耗。
Conventional current (+ → −) is the opposite of the actual electron flow (− → +) in a metal. Diagrams and formulas use the conventional direction — don't let the electron drift confuse you. And current only flows in a complete circuit.
常规电流(+ → −)与金属中实际的电子流(− → +)方向相反。图和公式都用常规方向——别被电子漂移弄糊涂。而且电流只在完整的电路中流动。
$6\ \text{C}$ of charge flows past a point in $3\ \text{s}$. What is the current?
- $I = \dfrac{Q}{t} = \dfrac{6}{3} = 2\ \text{A}$.
Double the charge in the same time and the current doubles to $4\ \text{A}$.
$6\ \text{C}$ 的电荷在 $3\ \text{s}$ 内流过某一点。电流是多少?
- $I = \dfrac{Q}{t} = \dfrac{6}{3} = 2\ \text{A}$。
同样时间内电荷加倍,电流就加倍到 $4\ \text{A}$。
Current is the rate of charge flow, $I = \dfrac{Q}{t}$ (in amperes), and needs a complete circuit. Conventional current flows + → −; in a metal the electrons actually drift − → +. Diagrams use the conventional direction.
电流是电荷的流动速率,$I = \dfrac{Q}{t}$(单位安培),需要完整的电路。常规电流从 + → −;在金属中电子实际漂移 − → +。图用常规方向。