Electric Current · 电流
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| current/ˈkʌrənt/ | 电流 | diàn liú |
| ampere/ˈæmpeə/ | 安培 | ān péi |
| conventional current/kənˈvenʃənl ˈkʌrənt/ | 常规电流 | cháng guī diàn liú |
| drift velocity/drɪft vəˈlɒsɪti/ | 漂移速度 | piāo yí sù dù |
What is actually "flowing" in a wire carrying electricity?
- Flip a switch and something moves through the wire at once.
- That something is charge — mostly free electrons drifting along.
- Current 电流 measures how fast that charge flows past a point.
- Everything about circuits starts from this one flow.
通电的导线里到底是什么在"流动"?
- 一按开关,就有某个东西立刻穿过导线。
- 那个东西就是电荷——大多是自由电子在漂移。
- 电流量度那份电荷流过某点的快慢。
- 关于电路的一切都从这个流动开始。
Current is the rate of charge flow
- Current is charge per unit time: $I = \dfrac{dQ}{dt}$.
- Its unit is the ampere 安培 (1 A $= 1$ C/s).
- Over a steady flow, the average is just $I = \dfrac{Q}{t}$.
- The derivative form catches a current that changes moment to moment.
电流是电荷流动的速率
- 电流是单位时间的电荷:$I = \dfrac{dQ}{dt}$。
- 它的单位是安培(1 A $= 1$ C/s)。
- 对稳定的流动,平均值就是 $I = \dfrac{Q}{t}$。
- 导数形式能捕捉时刻变化的电流。
Drive a current · 驱动电流
Build a simple loop and watch current flow around it from the battery. · 构建一个简单的回路并观察电流从电池出发绕其流动。
Electric current is: · 电流是：
$I = dQ/dt$ — charge passing a point per second. · $I = dQ/dt$ —— 每秒通过某一点的电荷量。
If $10\ \text{C}$ passes a point in $5\ \text{s}$, find the current (in A). · 如果 $10\ \text{C}$ 在 $5\ \text{s}$ 时间内通过某一点，求电流（单位：A）。
$I = Q/t = 10/5 = 2\ \text{A}$.
One ampere equals one coulomb per ____. · 一安培等于每 ____ 一库仑。
1 A $= 1$ C/s.
Conventional current runs the "wrong" way
- Conventional current 常规电流 points the way a $+$ charge would move.
- The actual electrons drift the opposite way (they are negative).
- We keep the convention because the physics works out the same.
- Arrows on a circuit always mean conventional (positive) current.
常规电流走"反"方向
- 常规电流指向 $+$ 电荷会移动的方向。
- 真实的电子朝相反方向漂移(它们是负的)。
- 我们保留这个约定,因为物理结果是一样的。
- 电路上的箭头总是表示常规(正)电流。
Conventional current points in the direction that: · 常规电流的方向是：
Conventional current follows a $+$ charge — opposite to electron drift. · 常规电流遵循 $+$ 电荷——与电子漂移方向相反。
Electrons drift slowly, the signal is fast
- Individual electrons crawl along at a drift velocity 漂移速度 of about a millimetre per second.
- Yet the light comes on instantly — the field pushes the whole line at once.
- Think of a full pipe of water: push one end, the far end moves right away.
- Slow drifters, fast message.
电子漂移得慢,信号却很快
- 单个电子以约每秒一毫米的漂移速度缓慢爬行。
- 可灯却立刻亮了——场同时推动整条线。
- 想象一根装满水的管:推一端,另一端立刻动。
- 漂移得慢,消息传得快。
Select all · 所有 true statements about current. · 选择关于电流的 所有 正确陈述。
Amps, opposite-to-drift convention, slow drift. A bulb uses energy, not current. · 安培，与漂移相反的惯例，慢速漂移。灯泡消耗能量，而非电流。
Current is conserved in a series wire
- In a single unbranched wire, the current is the same everywhere.
- Charge doesn't pile up or vanish — what flows in flows out.
- A bulb does not "use up" current; it uses up energy.
- The same amps that enter a series bulb also leave it.
电流在串联导线中守恒
- 在一根不分叉的导线里,电流处处相同。
- 电荷不堆积也不消失——流进多少就流出多少。
- 灯泡不"用掉"电流;它用掉的是能量。
- 进入串联灯泡的安培数也从它流出。
In a single series loop, the current is the same everywhere. · 在单个串联回路中，电流处处相同。
Charge is conserved: the same current flows through every series element. · 电荷守恒：相同的电流流过每个串联元件。
A wire carries $6\ \text{C}$ of charge past a point in $2\ \text{s}$.
- $I = \dfrac{Q}{t} = \dfrac{6}{2} = 3\ \text{A}$.
- Three coulombs stream past every second.
一根导线在 $2\ \text{s}$ 内有 $6\ \text{C}$ 电荷经过某点。
- $I = \dfrac{Q}{t} = \dfrac{6}{2} = 3\ \text{A}$。
- 每秒有三库仑流过。
A component uses energy, not current. The current leaving a bulb equals the current entering it — don't say the bulb "uses up" the amps. What drops across it is voltage (energy per charge), not current.
元件用掉的是能量,不是电流。从灯泡流出的电流等于流入的电流——别说灯泡"用掉"了安培数。降落在它上面的是电压(单位电荷的能量),不是电流。
Current is the rate of charge flow, $I = dQ/dt$, in amperes (C/s). Conventional current runs the way a $+$ charge would go (opposite to electron drift). In a series wire current is conserved — a component uses energy, not current.
电流是电荷流动的速率,$I = dQ/dt$,单位安培(C/s)。常规电流走 $+$ 电荷会去的方向(与电子漂移相反)。在串联导线中电流守恒——元件用能量,不用电流。