You can't get your head around it because it's the same as +V. You're thinking about it too much.
Voltage is just the difference of potential between two points. +Vdc between two points is -Vdc if you reverse your test probes. Usually the only need for having both +Vdc and -Vdc power sources is if you have to work with AC signals.
You are correct that AC net current flow is zero. It's not the flow of current that does the work, but your use of the current. Current is used when it gets dissipated into heat. This is when you start "losing" current.
(That last part was really hard for me to get into words. Someone please clarify it much better.)
I was thinking about motors, but isn't all the power still dissipated into heat, since magnetic fields are regenerative? I lack knowledge here.
I should say it's dissipated into radiation, so to include RF transmitters and lights.
As for the AC and "zero net current flow", you might think of it as a propogating wave like sound waves or water waves.. The air/water molecules have "zero net movement" (sometimes not even in the same direction as the wave!), but that doesn't mean the energy of the sound wave has "zero net movement". In fact, it is propogating in a single direction. You are transferring ENERGY, not necessarily electrons.You can't get your head around it because it's the same as +V. You're thinking about it too much.
Voltage is just the difference of potential between two points. +Vdc between two points is -Vdc if you reverse your test probes. Usually the only need for having both +Vdc and -Vdc power sources is if you have to work with AC signals.
You are correct that AC net current flow is zero. It's not the flow of current that does the work, but your use of the current. Current is used when it gets dissipated into heat. This is when you start "losing" current.
(That last part was really hard for me to get into words. Someone please clarify it much better.)
No. That would mean the motor no longer a motor, but an heat/EM source like a radio, light bulb, or x-ray because there is no energy left to be outputted as mechanical motion. I don't know what you mean by "magnetic fields are regenerative". To me that sounds like a buzz word. The magnetic fields being generated do work. The creation of the BEMF to oppose the voltage source for the motor is not regeneration. It does not "regenerate" anything.
Regenerative in the fact that the current used to create the field is recreated when the field collapses. This is for static inductors though. Although in a motor wouldn't this be apparent power - real power?
If it says +9V and -9V then you need two separate batteries or supplies (since the total voltage difference from the plus side to the minus side is 18V). You could use identical batteries and connect one with a negative terminal to ground and the other with a positive terminal to ground. A ground is just a common point for signal returns on a circuit. It may or may not go to earth ground.So, if you see a circuit diagram with +9V and -9V and ground symbols on it, rather than the standard battey sign with a thick short line an thin long line, is this effectivly the same thing? I saw a circuit with this +9V and -9V and it said you would nead a dual power supply? would a 9V battery work? also, where on this circuit would ground go to if its no from a AC plug?
Thanks for all your replies
Crutschow; So, if a circuit diagram has 2 points, one saying +9v another saying -9V, is this the same as a circuit diagram just having the battery symbol with +18v on the positive side and 0V on the negative side?
Hypothetically, if an 18V battery existed, would this work rather than using 2 9V batterys. Or is +9V and -9V used so different parts of the circuit can use 9V or 18V?
The ground point is typically the reference point (common) where all signal voltages are measured. Say you have a 1V signal, the reference point for that is circuit ground. The ground symbol is not needed but it saves showing a lot of wires on a schematic, making it less cluttered. All points with the ground symbol are wired together. On circuit boards this is often done with a ground plane consisting of a separate, complete layer of copper.One other thing then, in such circuits, there is often a ground point. I understand that in a high voltage appliance, the ground would connect to an earth pin etc.
However, on DC circuit diagrams, you often see +XV and - XV. Then certain connections throughout the circuit will lead to the ground symbol (The triangle made up of parallel lines).
What is this point, what physically would you wire those connections to? And if you don’t need to wire them to anything, why represent the connection on the circuit diagram?
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