These points each tend to have an effective value of between one and two cents.

每个点的有效价值往往在 1 到 2 美分之间。

So, in order to express current in this equation, we need a new variable that represents this effective value.

所以，为了在这个方程中表达电流，我们需要一个新的变量来表示这个有效值。