The quantities that describe the magnitude of alternating current include peak (and peak to peak), average, and effective value, with peak being the maximum value; The average value is the average of the relative value of alternating current (i.e. rectified) over a period of one cycle; The effective value is also known as the root mean square value (the formula on the first floor). Effective value: Direct current and alternating current are respectively passed through two identical resistive devices. If they generate equal heat within the same time, then the voltage and current of this direct current are taken as the effective value of this alternating current. So people generally say that the magnitude of voltage and current refers to the effective value unless otherwise specified. There is a certain relationship between the three: the ratio of the effective value to the average value is called the waveform factor KF; The ratio of peak to effective value is called the peak factor KP. For sine waves, the peak factor KP=root 2 (constant), and the waveform factor KF=2 times the root 2 (constant). And for non sine wave values, they will change. It is obvious that people are concerned about the effective value, but it is difficult to measure, and the average and peak values are easy to measure. Therefore, ordinary multimeters (including voltmeters, etc.) indirectly measure the effective value (according to the relationship of sine waves) by measuring the average or peak values. If the measured peak value is 10V, it should be displayed as 7.07V (effective value). These two types of tables display valid values, but they measure false valid values. Obviously, using these types of tables to measure sine waves is still relatively accurate, but measuring non sine waves is incorrect** A small table can directly measure the effective value (there are many methods), which means that it displays the effective value and measures the effective value. Therefore, this type of table is correct regardless of which waveform it measures. To distinguish between the first two types of tables, it is called true significant value.
