Electric voltage

Voltage

电压

Voltage is electric potential energy per unit charge, measured in joules per coulomb ( = volts). It is often referred to as "electric potential", which then must be distinguished from electric potential energy by noting that the "potential" is a "per-unit-charge" quantity. Like mechanical potential energy, the zero of potential can be chosen at any point, so the difference in voltage is the quantity which is physically meaningful. The difference in voltage measured when moving from point A to point B is equal to the work which would have to be done, per unit charge, against the electric field to move the charge from A to B. When a voltage is generated, it is sometimes called an "electromotive force" or emf.

电压是单位电荷的电势能，单位为焦耳每库仑（=伏特）。它通常被称为“电势”，这需要与电势能区分开来，因为“电势”是一个“单位电荷”的量。如同机械势能一样，势能的零点可以在任何点选择，因此电压的差值才是有物理意义的量。从点A移动到点B时测量到的电压差等于将电荷从A移动到B against 电场所需的功，单位电荷。当电压产生时，有时也被称为“电动势”或 emf。

Used to calculate current in Ohm's law.

用于计算欧姆定律中的电流。

Used to express conservation of energy around a circuit in the voltage law.

用于表达电路中能量守恒的电压定律。

Used to calculate the potential from a distribution of charges.

用于从电荷分布计算电势

Is generated by moving a wire in a magnetic field.

由在磁场中移动导线产生

Electromotive Force (EMF)

电动势（EMF）

When a voltage is generated by a battery, or by the magnetic force according to Faraday's Law, this generated voltage has been traditionally called an "electromotive force" or emf. The emf represents energy per unit charge (voltage) which has been made available by the generating mechanism and is not a "force". The term emf is retained for historical reasons. It is useful to distinguish voltages which are generated from the voltage changes which occur in a circuit as a result of energy dissipation, e.g., in a resistor.

当电池产生电压，或根据法拉第定律由磁力产生电压时，这种产生的电压传统上被称为“ electromotive force ”或 emf。emf 表示由发电机制提供的每单位电荷（电压）所拥有的能量，并非一种“力”。emf 一词保留下来是出于历史原因。有用的是区分由电路中由于能量耗散产生的电压，例如在电阻中产生的电压。

Motional EMF

运动电动势

The magnetic force exerted on the charges in a moving conductor will generate a voltage (a motional emf). The generated voltage can be seen to be the work done per unit charge. This motional emf is one of many settings in which the generated emf is described by Faraday's Law.

在运动的导体内，作用于电荷的磁力将产生电压（一种动生电动势）。所产生的电压可以看作是单位电荷所做的功。这种动生电动势是许多情况下生成的电动势被描述为法拉第定律的一种情形。

Note that the direction of the magnetic force is shown as the right hand rule direction on a positive charge, and shows the direction of the conventional current in the loop.

注意，磁场力的方向显示为正电荷的右手定则方向，并表示回路中 conventional current 的方向。

Voltage

Electromotive Force (EMF)

Motional EMF

Motional EMF and Faraday's Law