|
I hate to do post homework help but the internet isn't helping.
Basically my friends and I can't decide what happens to a voltage source if it is dangling. Let me clarify that, the other end, the negative end of the voltage source is hanging in the air, not connected to ground (because it is still there if it's connected to ground). We'd like to think that it can be removed, just like what happens to a resistor/capacitor/inductor when it dangles because current does not pass through it because of the lack of a closed loop. But since it's an independent source, the case might be different.
For some reason I believe it should still be there since the other end is just dangling, therefore, no additional voltage is coming in, and that is very very similar to the case when a voltage source is connected to ground.
Buuut, by conservation of charge, whatever the source gave should come back to that same source, since you can't just supply an infinite amount of voltage to the circuit and not get it back. And KVL actually supports this.....
So does it still stay in the circuit or is it removed? And what's the difference between a dangling voltage source and a grounded voltage source, if any. Any help will be appreciated. Thanks. I think we resolved it but I want to make sure.
|
I took a circuits class and I think the battery with one terminal disconnected does not affect a circuit in the long term.
|
if the circuit doesnt connect, then their wont be any current there.
do u mind giving a picture? your description is confusing
|
I think that your visualization of voltage is a little messed up. Voltage really can't be coming into anything, voltage is across something. Current is better thought of as something that actually goes through components. As for your question I drew up a really quick and dirty DC circuit with a resister (please forgive its crudeness). Basically if you disconnect the source as I have drawn there will be no voltage across the resistor because there is no current. If you were to measure across the gap in the wire you would simply measure the voltage the source was providing. You can actually test this out with a simple battery, resistor, and multimeter. Just hook them up as I have depicted and measure the voltage over the resistor and the gap in the wire.
As for the difference between a grounded source and this dangling scenario the main difference is simply in connectivity with components. Ground is used as the reference state for voltage measurement. If this is not the same for all components (ie: you don't have everything grounded properly) it can lead to some pretty dangerous build-up of charge ( think static electrical charge). Hopefully some of this helps.
Img:
+ Show Spoiler +
|
Fixed voltage sources don't have to have a current at all, they just force the two ends to have different potentials. Suppose you have a 5V source. You hook the positive end up to point A, and the negative end up to point B. The battery will make it so that point A is 5V above point B. Point be might be -2V relative to ground, so A would be +3V. If you hook point B up to ground (0V), point A will be +5V. If you hook point A up to ground, point B will be -5V. Basically it pushes them apart so there is 5 volts between them.
In your case it's hooked up to nothing, so it wouldn't affect the rest of the circuit and you can take it out. Point A would be dangling at 5V above point B, but it wouldn't matter to anything hooked up to point B.
|
United States5345 Posts
there is voltage but no current is flowing
|
So the positive terminal of the voltage source is connected to the circuit somewhere but the negative isn't grounded or otherwise connected to the circuit? In that case, the best you can do is to say the voltage source doesn't effect the circuit. In reality it could have an effect, but for simple circuit analysis with idealized sources it would be ignored.
|
I agree that your description is confused, but I think that your circuit won't work at all if both the power source is not connected on both sides. Either only current will flow through, or just POSITIVE amounts of voltage (depends on whether your power source has oscillatation function or not).
|
oh sorry I just replied now, and actually by KVL the voltage source can be omitted, I'll upload the picture later...
|
|
|
|
|
|
EPT![[image loading]](http://img27.imageshack.us/img27/2888/screenshot20100311at111.png)
