主要差异–rms与峰值

在交流电中，电流的大小总是变化的。因此，电流不仅可以用一个数字来描述，还可以用几个数字来描述。RMS和peak是两个可以用来表示交流电的数字。RMS和Peak的主要区别在于Peak是指交流电中电流能达到的最大值，而RMS是峰值电流除以二的平方根。

什么是峰(peak)？

Alternating currents change sinusoidally with time. Peak refers to the maximum value that the sinusoidally-varying current or voltage reaches. If the voltage  is expressed in the form , then the peak voltage is  .

Peak-to-peak refers to the absolute value of the difference between maximum and minimum voltages. Peak-to-peak voltages are sometimes used to describe alternating currents. If the wave is sinusoidal, then  .

什么是有效值(rms)？

RMS代表均方根。当一个量可以取负值和正值时，均方根用于表示该量的平均值。这是必要的，以便量的负值不会抵消任何正值。均方根用于热力学；例如，表示气体分子的平均速度。

因为交流电流中的电压是正弦变化的，如果我们取平均电压，我们会得到一个零的答案：

The area under a sin curve averages out to be 0.

相反，我们平方电流。现在，平方电流的平均值不是0，而是一半：

A sin squared curve. This has an average at 1/2.

Suppose a voltage is expressed as 

Suppose we want to find the average value of  . As we discussed earlier, one approach would be to first square the voltage. We do this now to both sides of the equation:

Next, we take the averges from both sides of the equation. The average of  is  . So,

如果我们要求平均电压，那么我们取平方根：

下图显示了交流电中的峰值电压、峰间电压和均方根电压。

A diagram showing peak, peak-to-peak and RMS voltages for a sine wave (PK=peak, PP=peak-to-peak, RMS=root mean square).

RMS voltage is useful in calculating the average power in a circuit. The average power  is given by  . In terms of the RMS current, the average power is given by  .

有效值(rms)和峰(peak)的区别

DPeak是指交流电中电流或电压达到的最大值。RMS给出电流或电压的平均值。

当引用交流电流的电压值时，通常引用的是RMS值。

RMS值总是小于峰值。

Image Courtesy:

“Graph of a sine wave voltage versus time (in degrees of angle) with RMS, peak, and peak-to-peak marked.” by AlanM1 (Derived from File:Sine wave 2.svg by en:User:Booyabazooka (CC0-licensed)) [CC0 1.0], via Wikimedia Comm***