众所周知 ,通过交流电流表和交流电压表读出的数值 ,都是有效值 .而交流电的有效值是根据电流的热效应来规定的 .但实际上交流电表工作的原理并不是依据电流的热效应 ,那么交流电表刻度盘上的数值是如何标度的呢 ?本文以中学生常用的磁电式中的整流式电表为例进行讨论 .1　磁电 As we all know, the values ​​read by the AC ammeter and the AC voltmeter are all valid values. The effective value of the AC is defined according to the thermal effect of the current. However, in fact, the principle of the operation of the AC meter is not based on the thermal effect of the current, so the AC How is the value on the meter dial scaled? This article discusses the example of a rectifying meter in the magnetoelectric type commonly used by middle school students.