Why can't a multimeter measure the polarity of alternating current?
The so-called alternating current means that its polarity changes alternately, and the speed of change is very fast. Whether it is a pointer-type or a more advanced general digital multimeter, it cannot reflect its instantaneous polarity. The number of times its polarity changes within a unit of time is called the frequency, and its unit is Hertz, which is a physical unit named in memory of the famous physicist Mr. Hertz. Because the polarity of this power source alternates, it is simply impossible to measure its polarity with an ordinary multimeter. If it is necessary to know the polarity at a certain moment, that is, its instantaneous polarity, the simplest method is to use an oscilloscope, an electronic instrument specially used to observe alternating current or direct current pulses.
The direction of alternating current changes at any time, and there is no concept of polarity. When it comes to measuring the live wire and the neutral wire, you can set the multimeter to the highest range for alternating voltage. Hold the black test lead with one hand and use the red test lead to detect the wire. If the pointer deflects, it is the live wire, and if it does not deflect, it is the neutral wire. In addition, some digital multimeters nowadays have the function of an electroscope.
Alternating current is an electric current whose magnitude and direction change periodically. It has no polarity but only frequency. The frequency of alternating current in our country is 50 Hertz, which means that the current changes back and forth 50 times per second, and the direction changes 100 times. There is something wrong with this question itself.
