if ac travels in both directions, and pulsating dc travels in both directions, it seems that pulsating dc would just match the definition of ac, if this isnt the case then what are the differences? when would we use pulsating dc instead of ac? And how is pulsating DC made?
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$\begingroup$ Electric fences commonly use pulsed DC. $\endgroup$– PM 2RingCommented Nov 22, 2019 at 11:58
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1$\begingroup$ What do you mean "difference?" What is it that you really want to know about "pulsed DC?" From a mathematical point of view, you can understand a "pulsed DC" signal as the superposition of a "pure" AC signal and a DC offset. $\endgroup$– Solomon SlowCommented Nov 22, 2019 at 16:17
2 Answers
Pulsed DC current changes in value, but not in direction. It's polarity does not change. In AC the polarity constantly changes. see https://en.wikipedia.org/wiki/Pulsed_DC
The very definition of AC and DC currents remain the same. Unless the direction of current is not reversed, a DC will never turn into AC current.
I remmeber my college days when the teacher draw a line which was sine wave but the wave itself remained in the same quadrant without changing its polarity. We are so used to associating a sine wave to AC current that all of the students were tricked into calling it a AC current wave while it definitely remained DC current.
Also I would like to mention this from ask any difference:
The key difference between AC and DC currents lies in the fact that the Direct current is steady and unidirectional i.e. the flow of electrons is always in the forward direction.
However, the Alternating current flows in multiple directions i.e. the movement of electrons is first in forward and then in the backward direction.