It's stay 0V because we assume that it's 0V all the time, but voltage on "A" node is equal -0.7VHi Guys
I have a question about AC and ground
when the polarity change in the AC voltage source ( like the following figure )
does the ground area become positive or stay 0 Volt ? What will happen to the ground ...
Right, that is how I was explaining there technically is no 0V for a ground. You can say that the reference point is 0V when in reality it may not be.vindicate, the measurements are kind of arbitrary. Say your transformer has a 12v secondary winding with ends A and B, and a centertap C. If you measure between A and B, you'll measure 12 volts. If you measure between A and C, or B and C, you'll measure 6 volts.
If you call C the common, you could say that with respect to C, ends A and B each measure 6 volts. So this is a 6-0-6 transformer.
If you call A the common, you could say that with respect to A, C measures 6 volts and B measures 12 volts. So this is now a 0-6-12 transformer.
Neither way is really wrong; they're just different ways of looking at it.
In other words, voltage, or an electrical potential, exsists between two points. It does not exsist at a single point alone. Ground then, has no charge, when compared to itself, even though magnetic flux and eddy currents surround us.any voltage measurement is taken from some point to a reference point. The reference point is that only, a point of reference. If you ask, does ground take on some charge?, that can only be answered if you specify in reference to what?
By grounding do you mean physically connected it to a source of ground(a water pipe, the ground wire on an outlet)? If that's what you mean, at least 90% of the linear wallwart transformers I've seen have had no source to ground.But if you ground one side of a circuit, and call it a reference point, then it is at 0 volts. It doesn't matter whether the circuit carries AC, or DC, or both. What other "reality" is there?
Great attachmentsIt's stay 0V because we assume that it's 0V all the time, but voltage on "A" node is equal -0.7V
Thats the exact answer I was looking for. Thanks for that.It is confusing when terms like "ground", "reference", "earth" are used interchangabily without being clear on how they're being.
I was using the term "ground" as in attach to a water pipe, but it doesn't make any difference for the voltage discussion.
You're right, many wallwarts are not grounded. They're cheaper that way, and usually the equipment they operate doesn't need grounding to run.
But with a transformer secondary, even if no terminal is actually grounded, you're still free to call one of the terminals your reference point. Then you could say that there is 6 volts from the reference point to one remote terminal, 12 volts from the reference point to the other remote terminal, or zero volts from the reference point to itself.
Or by choosing another terminal as the reference point, the other two terminals might both measure 6 volts.
You can pick any reference point you want because voltage is always measured between two points, like distance. You could say that the distance between your house and a train station is a mile, but it wouldn't make any sense to say that the distance of your house is a mile. Same with voltage - you could say that the voltage between two points is 6 volts, or that the voltage from a terminal to ground is 6 volts, but it makes no sense to say that a terminal measures 6 volts, unless it is clear what the reference point is.
In many circuits, there is a set of connections that are an unspoken reference point, often called ground even when it isn't actually grounded to Earth. This is so common that it is common practice to label individual points in a circuit with a voltage value. But in every case, those voltages are referred to the common point unless explicitly labeled.
|Thread starter||Similar threads||Forum||Replies||Date|
|S||PCB ground plane for multiple Vcc||General Electronics Chat||1|
|Short high frequencies to ground||Homework Help||14|
|What'll happen ,If I use any inductor on Audio Input Ground pin?||General Electronics Chat||2|
|1||Circuit to convert floating ground to ground reference||General Electronics Chat||14|
|Seeking ideas for buggy ground speed governor||Automation, Robotics & Control||92|
by Jake Hertz
by Steve Arar