Hi, I was wondering if someone could comment this:
https://qph.ec.quoracdn.net/main-qimg-0ab10d9f076e71356f8ba34ffdd189ed-c?convert_to_webp=true
which I found the web. I am trying to understand the difference between an AC signal and a DC signal. I understand that alternating current/voltage alternates between positive and negative. If the signal stays the whole time either positive or negative then it is a DC signal, correct? So, it can fluctuate(does not have to be linear) but as long is it stays positive or negative it is DC. If a signal keeps going positive, negative, positive, negative, then it is AC. The part I don't understand is the fifth picture where it says +ive A > -ive A and the very last picture where it says -ive > +ive. One can clearly see that the signal alternates between positive and negative in both cases. So I would think it is automatically AC? But in the picture the person has drawn a red line indicating that the average is positive in the first case and negative in the second case and designated both as DC signals. Is looking at the average some kind of special case or must we always look at the average amplitude to be certain whether or not a signal is indeed AC? Here's an example I drew of an exponential signal. The signal amplitude reaches positive 5 and goes down to negative 4. I would assume this an AC signal since it alternates, positive, negative. But the average is positive, so is it actually a DC signal?
https://qph.ec.quoracdn.net/main-qimg-0ab10d9f076e71356f8ba34ffdd189ed-c?convert_to_webp=true
which I found the web. I am trying to understand the difference between an AC signal and a DC signal. I understand that alternating current/voltage alternates between positive and negative. If the signal stays the whole time either positive or negative then it is a DC signal, correct? So, it can fluctuate(does not have to be linear) but as long is it stays positive or negative it is DC. If a signal keeps going positive, negative, positive, negative, then it is AC. The part I don't understand is the fifth picture where it says +ive A > -ive A and the very last picture where it says -ive > +ive. One can clearly see that the signal alternates between positive and negative in both cases. So I would think it is automatically AC? But in the picture the person has drawn a red line indicating that the average is positive in the first case and negative in the second case and designated both as DC signals. Is looking at the average some kind of special case or must we always look at the average amplitude to be certain whether or not a signal is indeed AC? Here's an example I drew of an exponential signal. The signal amplitude reaches positive 5 and goes down to negative 4. I would assume this an AC signal since it alternates, positive, negative. But the average is positive, so is it actually a DC signal?
Last edited by a moderator: