现象:图1是一个简单的半波整流电路。假使变压器B的次级交流电压有效值U为6V,在不接滤波电容器C的情况下,用直流电压表测得的整流输出电压Uo只有2.7V;但是,当接上一个100μF的滤波电容以后,用同样方法再去测量Uo时,电表的指示却是8.4V了。这是为什么呢? 平时我们所说的交流电压, 只要不加特别说明,一般都是指正弦交流电压。交流电压瞬时值 (用符号u表示) 的大小和方向都是随时间而变化的。它的最大值叫做峰值或称幅 Phenomenon: Figure 1 is a simple half-wave rectifier circuit. If the transformer B secondary AC voltage RMS U is 6V, without the filter capacitor C case, the DC voltage meter measured rectifier output voltage Uo only 2.7V; However, when connected to a 100μF filter capacitor , Use the same method to measure Uo, the meter’s indication is 8.4V. This is why? Usually we talk about the AC voltage, as long as without special instructions, usually refers to the sinusoidal AC voltage. The magnitude and direction of the ac voltage instantaneous value (symbol u) changes over time. Its maximum is called peak or amplitude