0.5 credit for either way as that would equal to 1.0 in some jurisdictions.

It took me a few seconds to catch the reference. Good one!

 

snce this is a word game, not a serious discussion about circuits, eledctricity, or electronics, I am not going to bother waisting any more time on it. voltage =emf, emf=voltage. and thats that.

 

snce this is a word game, not a serious discussion about circuits, eledctricity, or electronics, I am not going to bother waisting any more time on it. voltage =emf, emf=voltage. and thats that.

In general applications and discussions, I agree. No need to distinguish between the two.

 

Hi,

I see them as being both the same too, although in certain situations we like to clarify a true generation of voltage by calling it "EMF" rather than just voltage. We like to do this, but i dont think it is mandatory as some would like to put forth.

So 'EMF' would be a redundant form of 'voltage' where we want to indicate voltage but also want to show that it is being generated rather than just existing as a result of some voltage drop caused by an external generation of some sort.

Not too much difference:
"The voltage drop across the resistor was 10 volts".
"The EMF across the resistor was 10 volts".

Either one seems acceptable.


A little difference:
"The back EMF of the motor caused the operating current to decrease".
"The back voltage of the motor caused the operating current to decrease".

With this last one we usually like to say the first sentence, but i dont think it is mandatory.

In cases where we have both conditions in the same sentence it makes sense to use EMF, but again i dont think it is mandatory:
"The back EMF of the motor had shown up as a voltage drop across resistor R1".

wouldnt sound as good as:
"The back voltage of the motor had shown up as a voltage drop across the resistor R1", or as:
"The back voltage of the motor had shown up as an EMF across the resistor".

I think that is because phrases take on a life of their own sometimes and become more recognizable than some generic phrase. The phrase we are most familiar with is "back EMF" and dont hear "back voltage" too much if at all.

 

Ideally the improper inflection: "Voltage" would be abandoned altogether -- Sadly, that isn't likely to happen anytime soon...

 

then go to walmart and get a 12 emf battery. and find an emf meter while your there too.

 

then go to walmart and get a 12 emf battery. and find an emf meter while your there too.

I opined that "Voltage" should be abandoned -- NOT "Volt", "Volts" nor denominations thereof --- Now, inasmuch as the hourage is growing late I must be off! --- TTFN

 

how about some 120 EMFAC BULBS too?
by the way, electrical potential isnt the same as the wieght hanging by a wire having potential, or the "he has a lot of potential" either. correct usage is "plate potential" meaning plate voltage on a tube. and such.

 

how about some 120 EMFAC BULBS too?
by the way, electrical potential isnt the same as the wieght hanging by a wire having potential, or the "he has a lot of potential" either. correct usage is "plate potential" meaning plate voltage on a tube. and such.

The Volt is a unit of EMF -- Hence it's "some 120 Volt AC bulbs" --- All the same a 100 Watt lamp (as opposed to a 100 "wattage" lamp -- Or a lamp rated at a 'powerage' of 100) --- But that's not the verbal form in either case -- (i.e. It is voltage NOT 'volts' that should be substituted with 'EMF') --- I don't know what else to say...

by the way, electrical potential isnt the same as the wieght hanging by a wire having potential, or the "he has a lot of potential" either.

What was your first clue???

correct usage is "plate potential" meaning plate voltage on a tube.

How about:"correct usage is "plate potential" meaning plate EMF on a tube"

Style points please for not insisting upon 'anode'


Best regards
HP

 

You are confusing the concepts of potential and kinetic enery

No I'm not. I assure you i know the difference. However, the responses to my post indicate that I did not do a good job of explaining my point of view. I'm too tired to try to clarify, but maybe go back and reread with more benefit of doubt than indicated by this false statement.

 

With gunine respect: yes it is! 'Voltage' is a back-formed vulgarity that, owing to long use, we're stuck with! -- Why create a 30+ post thread in response to a simple request for clarification???

OK. You say it with such force and conviction, that it must be true.

 

OK. You say it with such force and conviction, that it must be true.

Not entirely -- It's now 50+ post thread

 

According to you, there should be no responses to this thread because the OP suggests that "emf and voltage are the same".

I say there should be responses, because voltage (no matter how much you dislike the term) is accepted terminology and references a general class or anything measured in volts, which includes emf and potential. There is at least potential which is measured in volts, and hence is a voltage, and is not the same thing as emf.

The discussion tries to give more detail about the nature of emf and potential, but I believe what I just said in the above paragraph answers the OP. EMF is not the same as voltage because emf is a subclass of "voltage".

The key thing about potential is that it relates to electrostatic conservative forces. But, emf is the thing that allow charges to be separated to create potential. Clearly, emf and potential are not exactly the same thing.

I still say definitions can be tricky. For example, if a very large capacitor is used as a battery, is it a potential with the leads flipped, or an emf? I say potential, but others say emf. I do not say they are wrong, even if I dont agree. I have never seen this question clearly answered in a text book and every time the question comes up among professionals, some people proclaim their view correct and best. I think it is like trying to argue whether a virus is life or not life. Some say a virus is life, some say it is not life. And, every time I use this example of how life is hard to define, someone retorts back that life is clearly definable. But, I know that the world is usually shades or grey and rarely black and white.

You prefer to see black in white, which is fine for me as well.

 

a general class or anything measured in volts, which includes emf and potential

And therein lies the misnomer... EMF and (electrical) potential are not distinct entities --- You are conflating a quantity with units thereof...
Shall we term 'dynamic' thrust 'force' -- and 'static' thrust 'Newtonage'?!

There is at least potential which is measured in volts

Indeed! - EMF is measured in Volts! -- One cannot measure anything in EMF because EMF is a quantity not a unit! --- But to your (apparent) point: I assert that EMF may be correctly, logically and, even, intuitively substituted for any and every (consistently applied) instance of ''Voltage'...

The key thing about potential is that it relates to electrostatic conservative forces. But, emf is the thing that allow charges to be separated to create potential.

if a very large capacitor is used as a battery, is it a potential with the leads flipped, or an emf?

Your statements are non-sequiturs --- A potential (actually potential difference) represents an EMF...

I think it is like trying to argue whether a virus is life or not life.

Respectfully, I fail to see the parallel -- on one hand we have a matter of consensus (CIP what characteristics define an organism) -- on the other it's purely a mater of semantics...

I know that the world is usually shades or grey and rarely black and white.

While I agree with the gist of that statement -- I feel we're not discussing the 'world' here ---But, rather, words...

Hey @Lool --- Inasmuch as we've both made our points -- and, moreover, that I think it most unlikely we'll change each-other's minds/perspectives -- what say we agree to disagree in the name of amity?

Best regards
HP

 

Perhaps some light can be shed on this by considering that potential and emf are definable even when there is no conductors, or charges. Consider free space, or vacuum with no charges or materials of any kind. Here, we can still define an emf for a loop in space, if there is a time changing magnetic field. This loop in space would also have an electric field that can be integrated around the loop. Basically, the electric field and time changing magnetic field are linked as an entity. The emf is expressible both as the time changing flux on the surface bounded by the loop, and as the integrated electric field around the loop. Both descriptions are entwined.

Now, normal electric potential has no meaning in this case. We know the voltage around the loop, but the voltage is path dependent if we use electric field to calculate it. There are not even any charges present to talk about a potential from charges.

For me, this is enough to highlight that there is a difference between potential and emf, even if we often are not very concerned about it in practice.

 

While I disagree -- I'll let you have the last word as a token of my sincere desire that a mere difference of perspective doesn't devolve into a bicker...

With sincere respect
HP

 

my response was not directed soley at you, and i'm not trying to bicker either. I'm just trying to add to the discussion. I dont expect anyone to agree with me, and I don't mind if you disagree either. Just food for thought, and certainly not the last word on the subject.

Basically, I'm saying I can see a difference between potential and emf. While related they are not exactly the same, in my mind, and I've seen experts on the subject also express the opinion that they are not exactly the same in all cases. Hence, this is relevant information for the op to consider.

 

This question does highlight a interesting subject of why some students sometimes have problems understanding transformers, motors and generators beyond simple rote formula calculations. Our typical experiences with forces like gravity (conservative), water, pressure combined with water analogies for electricity (voltage) IMO build mental models that tend to blur the distinction between them and non-conservative 'forces' like friction, air resistance and emf (induced and motional in the sense that it cannot be written as the gradient of a scalar field)
Non-conservative fields are 'created' by changing magnetic fields (and magnetic fields with changing electric fields). This is why transformers, motors and generators work and is the basis for countless claims of impossible perpetual motion machines by people who don't see this as a dissipative (mechanical energy is not conserved but lost as heat, etc...) process. It's not the magnetic field that causes charges to move on the secondary circuit loop, it's the induced electric field in the conductor caused by a changing magnetic flux.

This distinction is very important. It's not the way we normally think about voltage and current but it might be useful in a circuit.
http://www.maximintegrated.com/en/app-notes/index.mvp/id/2238

http://theory.uwinnipeg.ca/physics/work/node7.html
http://nuweb.neu.edu/bbarbiellini/phy1302/grad.htm

 

my response was not directed soley at you, and i'm not trying to bicker either. I'm just trying to add to the discussion. I dont expect anyone to agree with me, and I don't mind if you disagree either. Just food for thought, and certainly not the last word on the subject.

Basically, I'm saying I can see a difference between potential and emf. While related they are not exactly the same, in my mind, and I've seen experts on the subject also express the opinion that they are not exactly the same in all cases. Hence, this is relevant information for the op to consider.

Inasmuch as there seems to be some misapprehension as regards my 'intent' on this thread -- I offer yet another 'final' post

While I agree with your argument to the extent that distinct quantities may, owing to manifestation (Spec. mensuration) or analogy, be denominated in selfsame units (familiar examples being force vs Mass, work vs energy -- and, by dint of analogy, reactance vs resistance) --- I'm bound to say the (apparent) attempt to dichotomize 'static' vs 'dynamic' electrical phenomena owes to confusion of EMF with the field through which it acts? --- Granting that said assertion deserves more than 'cursory adjudication' - I'll leave that in abeyance...

The point of my argument on this thread is far more 'basic' -- To wit: It is my assertion that EMF and 'Voltage' are wholly synonymous terms -- Inasmuch as the 'Volt' is the unit of EMF and uniquely applicable thereto it follows that the sole quantity measurable in 'Volts' is EMF... Moreover I feel EMF is the preferred term inasmuch as 'Voltage' is a 'back formation' (unit-to-quantity)...

i'm not trying to bicker either.

I apologize if it seemed I was implying that you were --- My point was merely that little good comes from protracted exchanges following statement of each party's case...

Best regards
HP

 

Inasmuch as there seems to be some misapprehension as regards my 'intent' on this thread -- I offer yet another 'final' post

I apologize if it seemed I was implying that you were --- My point was merely that little good comes from protracted exchanges following statement of each party's case...

Best regards
HP

No misapprehensions here and no need to apologize. I was just clarifying that, like you, I am not trying to bicker, or make a protracted exchange. We both made points that may or may not help the OP.

Best Regards to you as well