Ill try to make it as clear as possible. This may seem like a simple question, but it is something that I havent quite figured out. It has to do with polarity on the leads of an AC source. Every book I read, pictures an AC source with two leads such as this:
Now, on the books, I see that the + symbol is used on upper lead, and the - at the bottom when they are picturing the positive half of the waveform, and they use a - symbol on the top and + on the bottom when they are picturing the negative half of the waveform. So far so good.
Here are the 3 scenarios and the thing that really confuses me:
Is only one lead changing voltage while the other stays stationary at 0V, meaning that the upper lead will go from + to - and from - to + and so on while the lower lead stays at 0v?
For the positive part of the waveform the upper terminal will be + and the lower 0V, and for the negative part of the waveform the lower terminal will be - and the upper 0v?
The upper terminal will have an alternating current and the lower terminal will have a mirror signal with opposite polarity? in which case, where is my 0v reference?
Comparing it to the AC wiring on any house, theres 1 cable which is "Hot" and the other which is the "neutral", I know the neutral doesnt carry any voltage and its the 0v reference, so the HOT cable is the one which changes its polarity.
Now, what exactly happens when I ground something? for example what is the difference of having that 0v floating or connected to ground, and what happens when I ground a circuit at something else rather than 0v? For instance say I have the following circuit: An ac source feeding a transformer, there are a couple of resistors across its secondaries and the mid point between the resistors is connected to ground.
So let say that the transformer has a 1:1 ratio and both resistors have the same resistance, 100ohms for this example, that means they will form a voltage divider of half the total voltage.
I know all that because thats how they thaught it to me, what I dont know is this, if ground potential is 0V, and my transformer's (bottom lead) is at 0v, why will I get a voltage at point B with respect to ground?
I get very confused between the diference of 0v and ground reference, and when I see circuits like the previous one which are grounded at some place different from 0V, specially on AC circuits. On DC it makes sense, if I ground the negative side or 0V side, I will have a positive voltage, if I ground the positive, I will get a negative voltage. But on AC it confuses me the fact that I dont know if the only alternating current is on one side of the terminals or if the 2 terminals are switching between each other.
It seems like on some cases its only one side (like in a house electrical installation) and on others like in a balanced push pull circuit its both sides.
It seems I dont have a clue of how exactly AC works.