This real voltage is called the terminal voltage.

这个实际电压称为端电压。

And you calculate the terminal voltage by subtracting the voltage drop due to internal resistance from the supplied emf voltage, designated by a script E.

然后通过从传递的电动势电压中减去由于内部电阻引起的电压降来计算端电压，用字母 E 表示。