Does the pointing vector theory hold true for DC current?

[gkangelexa]

Current and charge do not increase or decrease or get used up when going through a wire or other device. The amount of charge that goes in at one end comes out at the other end.

Where does the current go then, when I run electrical devices? If it is not used up when I turn on a light bulb or use the TV, where does it go?

 

[SteamKing]

It's called a ground for a reason.

 

[Drakkith]

Current is the flow of charges (in this case Electrons) through the conductor. Like you said the amount of current is the same at the beginning and end of the circuit. The current (charges) never go anywhere, they are always there. Imagine you have a pipe of water with a water pump that pumps it around the pipe in a circle. The water never goes anywhere but around the pipe, but the pump has to perform work on the water to keep it flowing because of resistance.

If you increase the resistance of the pipe then you have less water flowing by a particular point per second than the pipe with less resistance. Similarly, increasing the resistance of the circuit causes less current to flow at all.

It's called a ground for a reason.

Depending on what you mean by ground, that could be mean that it is the return wire for the circuit or that it is the safety wire in a household circuit that only transmits current to ground in a fault situation.

 

[gkangelexa]

So then what do electric companies charge you for? The voltage they provide that is necessary for the current?

 

[Drakkith]

So then what do electric companies charge you for? The voltage they provide that is necessary for the current?

They charge you because it takes work to produce electricity. To produce the voltage that determines the current in a circuit you have to use energy. Typically power plants use fossil fuels or nuclear power to heat water which then turns a steam turbine. The turbine turns a generator which produces the power. The key here is that when the generator is turning there is resistance to it. The more power drawn from the generator the greater the resistance to the generator turning and the more power has to be input to the generator. You are paying for the fuel, infrastructure, employees, ETC.

 

[DaveC426913]

So then what do electric companies charge you for? The voltage they provide that is necessary for the current?

The work done. It does power your lights. Energy is flowing into your house as useful electricity and leaving as waste heat.

 

[pallidin]

Current ... do(es) not increase or decrease or get used up when going through a wire or other device.

Yes it does. That's the whole idea.

 

[russ_watters]

Yes it does. That's the whole idea.

No, it really doesn't. The current at any place in a continuous, brancless circuit is the same.

 

[pallidin]

Uh, no. A resistive device within the circuit will reduce current flow.

 

[BobG]

Drakkith's answer is just about perfect.

Current is the rate of flow.

In this case, the things that are moving (or flowing) are electrons (and the electrical charge associated with those electrons). In an electric circuit, especially if it's AC, those electrons aren't actually going anywhere - they're just moving around in your wires.

You're paying to have those electrons moved for you, not for the electrons. Just like in Drakkith's example, where the water is yours, but you're paying to run the pump that moves the water around for you.

 

[Drakkith]

Uh, no. A resistive device within the circuit will reduce current flow.

Yes, the current throughout the circuit will be reduced, correct?
The current isn't going anywhere or being used up. There is simply less because of the resistance. I think that's what both of you are saying.

 

[pallidin]

Yes, the current throughout the circuit will be reduced, correct?
The current isn't going anywhere or being used up. There is simply less because of the resistance. I think that's what both of you are saying.

Well, it IS being used up, in a sense. It HAS to be, else one would have perpetual motion with infinite energy draw.
The key is "conversion" A specific amount of current flow is reduced, by conversion, to, say, heat or light. Thus there IS less current.

 

[phinds]

Well, it IS being used up, in a sense. It HAS to be, else one would have perpetual motion with infinite energy draw.
The key is "conversion" A specific amount of current flow is reduced, by conversion, to, say, heat or light. Thus there IS less current.

No, the heat or light is produced by the work done at the power station in moving the electrons around the circuit loop. To get more current to produce a brighter light, the power station has to do more work. The current isn't used up at all. What's used is the work being done at the power station. That's what you are paying for (well, that and all those wires that the power company has to maintain).

 

[pallidin]

I would confidently say that my 1500 watt electrical space heater is, in fact, initially reducing current at IT'S LOCATION, not the power station.
The "power station" must then ramp-up current flow to compensate for the losses at my space heater's location.
Thus the "bill"

 

[Naty1]

current is loosly bound electrons moving along from atom to atom in a conductor...they don't "disappear...

Perhaps what you are thinking about is energy (power)...THAT is what is being consumed by electrical appliances...electrons don't disappear in loads anymore than they are produced at generating devices.

palladin: try reading about Kirchoff's current law.

 

[DrGreg]

I would confidently say that my 1500 watt electrical space heater is, in fact, initially reducing current at IT'S LOCATION, not the power station.
The "power station" must then ramp-up current flow to compensate for the losses at my space heater's location.
Thus the "bill"

When your heater is switched off, there's zero current through it, so when it's switched on it's increasing the current, not reducing it. But it does cause a small drop in voltage, which the power station has to compensate for.

 

[pallidin]

current is loosly bound electrons moving along from atom to atom in a conductor...they don't "disappear...

Perhaps what you are thinking about is energy (power)...THAT is what is being consumed by electrical appliances...electrons don't disappear in loads anymore than they are produced at generating devices.

palladin: try reading about Kirchoff's current law.

I never said or suggested that the actual electrons are "consumed"
Rather, what I am saying is that the energy during the event most cetainly is(rather converted) to heat, light, etc...
That event requires a reduction in current flow.

 

[Naty1]

That event requires a reduction in current flow.

no.

where do you think the electrons go??

you have energy and current confused.

 

[pallidin]

When your heater is switched off, there's zero current through it, so when it's switched on it's increasing the current, not reducing it. But it does cause a small drop in voltage, which the power station has to compensate for.

Look, it's very simple: Resistive devices in an electrical circuit DISSIPATE energy.
This action necessarily results in a quantifiable reduction in current flow.

 

[pallidin]

OK, everyone. A reduction in electron "flow" DOES NOT in any way mean a loss of the specific electrons themselves...

 

[DrGreg]

Look, it's very simple: Resistive devices in an electrical circuit DISSIPATE energy.
This action necessarily results in a quantifiable reduction in current flow.

When you talk about a reduction of current, please specify precisely which two currents are being compared.

 

[phinds]

I would confidently say that my 1500 watt electrical space heater is, in fact, initially reducing current at IT'S LOCATION, not the power station.

Then I would confidently say that you should study electricity more.

 

[pallidin]

Then I would confidently say that you should study electricity more.

I must respectfully say that, IMHO, you are wrong. Love you and cheers :)

 

[russ_watters]

Pallidin, you need to learn the definitions of the words you are using. "Current" is a flow rate of charge -the number of electrons flowing past a point in a circuit. It is NOT synonymous with energy or power.

If the flow rate of electrons were different in different parts of a circuit, they would have to disappear or be created. Just like the flow rate of water through a pipe.

 

[phinds]

I must respectfully say that, IMHO, you are wrong. Love you and cheers :)

Pallidin,

I completely get that you are not being rude and I take no offense at your disagreement. As Russ said, you seem to be confused about the terms being used. I haven't opened any of my Electrical Engineering textbooks in over 40 years, but I don't really need to look this one up to know what's right.

Your opinion (and mine as well for that matter) are irrelevant to the situation. Facts are facts and electricity is a well understood phenomenon at the macro level we are talking about.

The only way you can push any amount of current out one end of a power line is to get the same amount of current back in the other end of the line. What it does in between can cause the voltage across the line to drop if the power being supplied is insufficient to drive the voltage*current power load but the only way for the current to be reduced at the load is for the power station to drive out (and get back) less current.

 

[sophiecentaur]

I would confidently say that my 1500 watt electrical space heater is, in fact, initially reducing current at IT'S LOCATION, not the power station.
The "power station" must then ramp-up current flow to compensate for the losses at my space heater's location.
Thus the "bill"

You should really bone up on this before you "confidently say" something. Learn what Current Volts, Power and all the other quantities are.

Would you say that there are a different number of links in your bicycle chain entering your rear wheel sprocket than links entering your chain wheel sprocket when you are powering up hill? 'Cos that's as wrong as what you are implying about current flow.

 

[phinds]

Would you say that there are a different number of links in your bicycle chain entering your rear wheel sprocket than links entering your chain wheel sprocket when you are powering up hill? 'Cos that's as wrong what you are implying about current flow.

Excellent analogy, nicely put.

 

[pallidin]

Excellent analogy, nicely put.

Not so fast... that a REALLY bad analogy.
I'll leave it to you to understand why.

 

[DrGreg]

Not so fast... that a REALLY bad analogy.
I'll leave it to you to understand why.

So we're supposed to read your mind to find out why you think a good analogy is bad?

 

[Drakkith]

Not so fast... that a REALLY bad analogy.
I'll leave it to you to understand why.

It seems perfectly fine for an analogy to me. After all, it's just an analogy. The force you apply to the pedals is the voltage, the chain is the current, the resistance is the hill. Seems perfectly fine to me. It ain't perfect, but it works.