What is the difference between ac and dc?

What is the difference between ac and dc? 2019 - 11 - What is the difference between ac and dc 20? Alternating current (ac) and direct current difference is as follows: first, an alternating current is negative direction of uncertainty, moment as a cyclical change, such as residents use 220 v, 50 hz ac mains, 50 cycles per second, transform the positive and negative direction one hundred times; Two, alternating current (ac) high and low voltage and current intensity also with the cyclical change, and the existence and alternating current (ac) cycle, the zero moment of similar zero moment in the circuit without current or tend to be small; Three, alternating current (ac) by perceptual load, will produce self-induction phenomenon, using the electromagnetic induction principle of transformer can easily change the ac voltage ( Can boost pressure can be reduced, but also can make the equivalent output isolation) ; Four, alternating current (ac) can use the principle of electromagnetic induction and transformer, can be different power allocation and line impedance matching, lets each circuit to obtain different corresponding power, and ensure that each part of the independent and mutually influence; Five, proper frequency and voltage alternating current (ac) ( Especially three-phase alternating current) To the perceptual load ( Or capacitive load) Can produce special effects, such as make the three-phase induction motor produces work directly. Alternating current (ac) of the above characteristics, compared with direct current (dc) what is the direct current (dc) does not have great advantage; Direct current (dc) across the electrodes feature is fixed, the circuit of current direction invariable, the current weak periodic size will not change, cannot use to transformer dc in the transformer, the perceptual load to the dc inductance is zero, in short, direct current (dc) compared to an alternating current is different, all kinds of instruments and electrical equipment of the internal circuit were extensive use of direct current, but external for electricity still can make the alternating current (ac), but you need to use the rectifier filter circuit, converts alternating current to direct current, just can make the circuit work normally. Direct current power supply circuit, if you use ac power directly, the circuit can not run normally, even completely damaged, this is a dc voltage in comparison with the unique advantages of alternating current (ac). Only fully understand the features and advantages of ac dc, in order to better take advantage of them. What is the ac dc is what?