Electricity question

[JohnCU]

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

 

[jagec]

Originally posted by: JohnCU

Originally posted by: element
you spent 2 years in EE and don't know the answer to your question? I hate to say this but that's sad

Well, relative to the ground, the battery's positive end is at 1.5 V, no?

No, as previously mentioned, one end of the battery is 1.5V relative to the OTHER end, not relative to any ground.

If you connect one end of a battery to a 1000V DC power supply, and measure across the battery, it will still read 1.5V

AC/DC has nothing to do with it, since you're not measuring anything having to do with AC anyway.

 

[RaynorWolfcastle]

The short answer is that there is nothing generating a potential difference between the two prongs of your voltmeter.

 

[Pepsi90919]

Originally posted by: JohnCU

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

yeah, if you actually connected it to the battery

 

[JohnCU]

Originally posted by: Pepsi90919

Originally posted by: JohnCU

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

yeah, if you actually connected it to the battery

right... so i'm just saying there is no current flowing either way

 

[Heisenberg]

Having a potential difference between two points has nothing to do with completing a circuit. The electric potential comes from the sole fact that an electric field is a conservative vector field, and so can be described by a scalar potential.

 

[RaynorWolfcastle]

Originally posted by: Heisenberg
Having a potential difference between two points has nothing to do with completing a circuit. The electric potential comes from the sole fact that an electric field is a conservative vector field, and so can be described by a scalar potential.

That's the (slightly) more complicated explanation, but if he's asking this question to start with, I don't think this is the explanation he's looking for.

 

[Pepsi90919]

Originally posted by: JohnCU

Originally posted by: Pepsi90919

Originally posted by: JohnCU

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

yeah, if you actually connected it to the battery

right... so i'm just saying there is no current flowing either way

no that's what everyone else was trying to tell you

 

[element]

Originally posted by: JohnCU

Originally posted by: Pepsi90919

Originally posted by: JohnCU

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

yeah, if you actually connected it to the battery

right... so i'm just saying there is no current flowing either way

there doesn't have to be current flowing for there to be a potential difference, that's why it's called a POTENTIAL difference. It has potential for current flow, not currently doing so (no pun intended)

 

[Heisenberg]

Originally posted by: RaynorWolfcastle

Originally posted by: Heisenberg
Having a potential difference between two points has nothing to do with completing a circuit. The electric potential comes from the sole fact that an electric field is a conservative vector field, and so can be described by a scalar potential.

That's the (slightly) more complicated explanation, but if he's asking this question to start with, I don't think this is the explanation he's looking for.

Yeah, I know, but the whole "needing to complete a circuit to have a potential thing" isn't right so I wanted to clear up any misconceptions.

 

[JohnCU]

Originally posted by: element

Originally posted by: JohnCU

Originally posted by: Pepsi90919

Originally posted by: JohnCU

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

yeah, if you actually connected it to the battery

right... so i'm just saying there is no current flowing either way

there doesn't have to be current flowing for there to be a potential difference, that's why it's called a POTENTIAL difference. It has potential for current flow, not currently doing so (no pun intended)

I know, that's what I was trying to tell the other people who said no current was flowing.

 

[morkinva]

you need to complete the circuit.... preferably with your tongue

 

[Colt45]

Originally posted by: JohnCU

Originally posted by: Pepsi90919

Originally posted by: JohnCU

Originally posted by: Pepsi90919
i don't see where you're going with this...

The voltmeter does not complete a circuit with the battery, it's supposed to be infinitely resistive.

yeah, if you actually connected it to the battery

right... so i'm just saying there is no current flowing either way

An *ideal* voltmeter would be infinitely resistive, because it wouldn't alter the circuit. but it is impossible in real life. V=RI... you can never run from this

 

[Stealth1024]

Originally posted by: Pepsi90919
well for one thing you can't read AC and DC at the same time... among lots of other things

the neutral in a wall socket is not AC or DC this has nothing to do with it...

 

[JohnCU]

I love ATOT. "You've been in EE and don't know this?" and half of you have given me the wrong answer.:thumbsup:

 

[element]

Originally posted by: Stealth1024

Originally posted by: Pepsi90919
well for one thing you can't read AC and DC at the same time... among lots of other things

the neutral in a wall socket is not AC or DC this has nothing to do with it...

it most certainly is AC when current is flowing through it

 

[element]

Originally posted by: JohnCU
I love ATOT. "You've been in EE and don't know this?" and half of you have given me the wrong answer.:thumbsup:

yeah but those people spouting off wrong answers haven't been in EE for 2 years I'll bet.

 

[JohnCU]

Originally posted by: element

Originally posted by: Stealth1024

Originally posted by: Pepsi90919
well for one thing you can't read AC and DC at the same time... among lots of other things

the neutral in a wall socket is not AC or DC this has nothing to do with it...

it most certainly is AC when current is flowing through it

Ground is ground, it's 0, it doesn't alternate between +0 and -0.

EDIT: If it didn't stay 0, you couldn't use node-voltage to analyze the circuit...

 

[jagec]

Originally posted by: Stealth1024

Originally posted by: Pepsi90919
well for one thing you can't read AC and DC at the same time... among lots of other things

the neutral in a wall socket is not AC or DC this has nothing to do with it...

yeah, really. There's nothing magical about the neutral in a wall socket, you can complete the circuit just as easily by using the live wire, and a fork stuck in the ground.

 

[JohnCU]

Originally posted by: element

Originally posted by: JohnCU
I love ATOT. "You've been in EE and don't know this?" and half of you have given me the wrong answer.:thumbsup:

yeah but those people spouting off wrong answers haven't been in EE for 2 years I'll bet.

Yes, and I'm just now finishing my second circuits class. 2 circuits classes doesn't exactly provide me with all the answers.

 

[Eli]

Oh boy .................

Well, no.. because you are not completing the circuit. With 40+ posts, I'd hope that at least has already been covered..

Look at it this way, the electrons are trying to get back to the battery.

If you have a wire connected to the + side.. the electrons are going to start marching through the wire... they'll encounter your voltmeter... continue through it, and into the neutral wall wire.

Now, where are they going to go? Keep marching off into oblivion, traversing millions of miles of copper wire? Back to the power station?

In reality, they never started marching in the first place, since there was no circuit. But you get the idea.

 

[eelw]

Originally posted by: JohnCU

Originally posted by: element

Originally posted by: JohnCU
I love ATOT. "You've been in EE and don't know this?" and half of you have given me the wrong answer.:thumbsup:

yeah but those people spouting off wrong answers haven't been in EE for 2 years I'll bet.

Yes, and I'm just now finishing my second circuits class. 2 circuits classes doesn't exactly provide me with all the answers.

How can you not learn to complete the circuit until your 2nd year!!!!!! Amazing how the school system is going down the drain now.

 

[JohnCU]

Originally posted by: Eli
Oh boy .................

Well, no.. because you are not completing the circuit. With 40+ posts, I'd hope that at least has already been covered..

Look at it this way, the electrons are trying to get back to the battery.

If you have a wire connected to the + side.. the electrons are going to start marching through the wire... they'll encounter your voltmeter... continue through it, and into the neutral wall wire.

Now, where are they going to go? Keep marching off into oblivion, traversing millions of miles of copper wire? Back to the power station?

In reality, they never started marching in the first place, since there was no circuit. But you get the idea.

But a voltmeter is supposed to be INFINITELY resistive, the electrons wouldn't be able to move through it anyway, so you don't need a completed circuit to measure potential.

 

[jagec]

Originally posted by: element
it most certainly is AC when current is flowing through it

...which is doesn't in this case.

 

[TheLonelyPhoenix]

Wow. I thought the math/science threads were bad... this is WRETCHED. Half the people in this thread have completely pulled answers out of their asses.

*pulls up a lawnchair*

Keep it up, boys. I haven't had enough entertainment today.