Ummm....any component without a zero average value is, by definition, not AC!Note that this equation is only valid for AC waveforms with a 0 average value.
Not sure about the definition of AC but some waveforms which have both positive and negative peaks do not have zero average.Ummm....any component without a zero average value is, by definition, not AC!
And therefore have one or more AC components with a single DC component with a magnitude of the average value.Not sure about the definition of AC but some waveforms which have both positive and negative peaks do not have zero average.
I agree that varying signals where the current does not change direction are not consider AC.The distinction between AC and rippling DC comes up often. Some - most I think - would say the ripple on a DC signal is the AC component on top of a DC voltage. Any time-varying element to voltage = AC.
I personally am resolved to reserve the term AC for circuits where the current actually alternates direction, not just magnitude. It's just a semantic difference but I hope to be a little more precise in my language. Unfortunately this distinction depends on the circuit, not the signal itself. If there's any time-varying element, you could always construct a circuit to produce an alternating current.
That's true. But it's also true that the term "DC" can be and often is applied to the same signal that would be called "AC" by that definition. Consider the output of a wall wart or even a half-wave bridge. Definitely labeled "DC" despite the same rippling that many would call "AC".... in common engineering use it refers to any time varying signal, independent of the actual current direction.
One can propose "interesting" circuit behavior in which an AC voltage source driving an ideal inductor introduces a DC offset to the current without having a DC source or rectifier elements, etc.Why should a signal go from AC to not-AC just because you add a DC level shift?
Barring specifying a suitable set of initial conditions, you would need some kind of non-linear element.One can propose "interesting" circuit behavior in which an AC voltage source driving an ideal inductor introduces a DC offset to the current without having a DC source or rectifier elements, etc.
Is "cookie problem" a common phrase? I've never heard of it except when talking about web browsers.I was thinking the same thing. Perhaps use it as a "cookie problem" for class.
Wayne,I personally am resolved to reserve the term AC for circuits where the current actually alternates direction, not just magnitude. It's just a semantic difference but I hope to be a little more precise in my language. Unfortunately this distinction depends on the circuit, not the signal itself. If there's any time-varying element, you could always construct a circuit to produce an alternating current.
Nope. It means that I throw out an optional problem to the class for them to go away and work on and submit as soon as they have an answer. The first person to submit a correct answer gets one of the large chocolate chip cookies that places in some shopping malls sell (they are typically 8" to 12" in diameter) that I buy on my own dime. It's something that one of my colleagues at the Air Force Academy did when I was teaching there.Is "cookie problem" a common phrase? I've never heard of it except when talking about web browsers.
Ah, good idea but i am sorry to hear it is not costing you much.Nope. It means that I throw out an optional problem to the class for them to go away and work on and submit as soon as they have an answer. The first person to submit a correct answer gets one of the large chocolate chip cookies that places in some shopping malls sell (they are typically 8" to 12" in diameter) that I buy on my own dime. It's something that one of my colleagues at the Air Force Academy did when I was teaching there.
Alas, sadly, I find that few people even attempt the problems, so it costs me very little money.
why isnt this just Vrms= Vac+Vdc???It gives you the RMS amplitude of the AC component of a waveform that consists of an AC component riding on a DC component (i.e., a DC offset or a non-zero average value).
It comes from the more fundamental relationship that
Vrms^2 = Vdc^2 + Vac^2
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