Electric Potential · 电势
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| volt/vəʊlt/ | 伏特 | fú tè |
Voltage is like "electric height"
- A ball rolls downhill from high ground to low; a positive charge "rolls" from high voltage to low.
- Voltage measures the electric potential energy per unit charge at a point.
- It is like the height of an electric landscape — energy waiting to be released.
- The difference in voltage between two points is what drives current in a circuit.
电压就像"电学高度"
- 球从高处滚向低处;正电荷从高电压"滚"向低电压。
- 电压量度一点处单位电荷的电势能。
- 它就像一片电学地貌的高度——等待释放的能量。
- 两点之间电压的差,正是驱动电路中电流的东西。
Potential is energy per charge
- Electric potential $V$ is potential energy per unit charge: $V = \dfrac{U}{q}$.
- Its unit is the volt 伏特 ($1\ \text{V} = 1\ \tfrac{\text{J}}{\text{C}}$).
- Unlike the field, potential is a scalar — just a number at each point, no direction.
- For a point charge, $V = \dfrac{kq}{r}$, falling off as $1/r$.
电势是单位电荷的能量
- 电势 $V$ 是单位电荷的势能:$V = \dfrac{U}{q}$。
- 它的单位是伏特($1\ \text{V} = 1\ \tfrac{\text{J}}{\text{C}}$)。
- 与场不同,电势是标量——每一点只是一个数,没有方向。
- 对点电荷,$V = \dfrac{kq}{r}$,按 $1/r$ 衰减。
Field and potential together · 场与电势的结合
See how the field lines relate to the potential that falls off around a charge. · 查看场线与围绕电荷衰减的电势之间的关系。
Electric potential is a scalar — a single number at each point, with no direction. · 电势是标量——每一点的一个数值，没有方向。
Unlike the field, potential has no direction; it is a scalar in volts. · 与场不同，电势没有方向；它是伏特单位的标量。
One volt equals one joule per ____. · 一伏特等于每____一焦耳。
$1\ \text{V} = 1\ \tfrac{\text{J}}{\text{C}}$ — energy per unit charge. · $1\ \text{V} = 1\ \tfrac{\text{J}}{\text{C}}$ — 单位电荷的能量。
Equipotentials and potential difference
- Points at the same potential form equipotential surfaces (circles around a point charge).
- No work is needed to move a charge along an equipotential.
- The potential difference $\Delta V$ between two points is the "voltage" between them.
- The energy to move a charge $q$ through $\Delta V$ is $W = q\,\Delta V$.
等势面与电势差
- 电势相同的点构成等势面(点电荷周围的圆)。
- 沿等势面移动电荷不需要做功。
- 两点之间的电势差 $\Delta V$ 就是它们之间的"电压"。
- 把电荷 $q$ 移过 $\Delta V$ 所需的能量是 $W = q\,\Delta V$。
How much energy is needed to move a $2\ \text{C}$ charge through a potential difference of $6\ \text{V}$? Answer in $\text{J}$. · 将一个$2\ \text{C}$电荷移动$6\ \text{V}$的电势差需要多少能量？答案单位为$\text{J}$。
$W = q\Delta V = 2 \times 6 = 12\ \text{J}$.
How much work is needed to move a charge along an equipotential surface? · 沿等势面移动电荷需要做多少功？
Points on an equipotential are at the same potential, so no work is needed to move between them. · 等势面上的点具有相同电势，因此在它们之间移动不需要做功。
Select all · 所有 true statements about electric potential. · 选择所有关于电势的正确陈述。
Potential is a scalar in volts, and its difference drives current. Only the field has a direction. · 电势是以伏特为单位的标量，其差值驱动电流。只有场才有方向。
Why it matters for circuits
- A battery maintains a fixed potential difference across its terminals.
- That voltage is the "push" that drives charges around a circuit.
- Charges flow from high potential to low, releasing energy in the components.
- So potential is the bridge from static charges to working circuits (next topic).
它对电路为何重要
- 电池在两端维持一个固定的电势差。
- 那个电压就是驱动电荷绕电路运动的"推力"。
- 电荷从高电势流向低电势,在元件中释放能量。
- 所以电势是从静止电荷到工作电路的桥梁(下一主题)。
Which correctly distinguishes potential from field? · 哪项正确区分了电势与场？
Potential $V = U/q$ (scalar, volts); field $E = F/q$ (vector, N/C). · 电势$V = U/q$（标量，伏特）；电场$E = F/q$（矢量，N/C）。
Don't confuse potential $V$ (a scalar, in volts) with the field $E$ (a vector, in $\tfrac{\text{N}}{\text{C}}$). Potential is energy per charge; the field is force per charge. And only differences in potential do work — the zero point is your choice.
不要把电势 $V$(标量,单位伏特)和场 $E$(矢量,单位 $\tfrac{\text{N}}{\text{C}}$)弄混。电势是单位电荷的能量;场是单位电荷的力。而且只有电势的差才做功——零点由你选择。
How much energy does it take to move a $2\ \text{C}$ charge through a potential difference of $6\ \text{V}$?
- $W = q\,\Delta V = 2 \times 6 = 12\ \text{J}$.
That is the energy the charge gains (or gives up), depending on direction.
把一个 $2\ \text{C}$ 的电荷移过 $6\ \text{V}$ 的电势差需要多少能量?
- $W = q\,\Delta V = 2 \times 6 = 12\ \text{J}$。
那是电荷获得(或放出)的能量,取决于方向。
Electric potential $V = U/q$ (in volts) is the potential energy per unit charge — a scalar, like "electric height". For a point charge $V = kq/r$. The potential difference ($\Delta V$, the voltage) drives current, and moving charge $q$ through it takes energy $W = q\,\Delta V$.
电势 $V = U/q$(单位伏特)是单位电荷的势能——一个标量,像"电学高度"。对点电荷 $V = kq/r$。电势差($\Delta V$,即电压)驱动电流,把电荷 $q$ 移过它需要能量 $W = q\,\Delta V$。