[sacrosancty]

I still have trouble working out the difference between electromotive force and potential difference. Teachers do a poor job of that one. I imagine it was even more of a blurry muddle to everyone back then.

But if you don't define your variables, an equation becomes a bit useless. Was it really that Ohm didn't use the "gate-kept" language or that he didn't actually know what he was talking about?

[dmitriid_y]

With the benefit of history, we know Ohm was more right than wrong. So -- even if these critics where hitting on a very real inconsistency of Ohm's research in their pursuit of the virtue of peer review -- they fell victim to the arrogance of their ivory tower.

The pitch-perfect critique would've had to be "You've got some great work, but this bit here is hard to follow or outright inconsistent". Instead, they shouted him out of the profession because of the surety of their convictions.

[hattmall]

This is still a huge problem today because at a certain level most people's benefit proposition switches from the pursuit of discovery to maintenance of the status quo.

[robocat]

https://www.electronics-notes.com/articles/basic_concepts/vo...

EMF is a DC voltage present even in an open circuit, when no current is drawn. EMF comes from a cell/battery or DC generator. EMF is the cause; potential difference is the effect.

[sacrosancty]

But potential difference exists when there's no current drawn too. That's just more confusion.

One aspect I'd noticed is that EMF doesn't necessarily have a corresponding potential difference. Eg. a generator with the output short-circuited still has the same EMF as if it was open circuit but potential difference is zero or near-zero across any two points in its windings or circuit.

[projektfu]

The potential difference can be measured between any two points in a circuit, but EMF is the source of electrical energy such as a battery or generator that produces the potential difference that can be considered to "drive" the circuit.

As I understand it, an EMF has to come from nonelectrical energy, such as chemical, thermal, mechanical, or electromagnetic energy. So if you are drawing your circuit with a battery, you could call that EMF but if you are drawing it with a generic voltage source, you would not call that EMF per se.

[sacrosancty]

That 2nd distinction seems weirdly unreal. Is there an example of a real generic voltage source that only uses electrical energy and not those other types, or are you just referring to an idealization that you might use in a circuit diagram?

[projektfu]

Many voltage sources are themselves circuits and the EMF element would be hidden therein.

[sacrosancty]

Hmm. So is it that an EMF can't be carried along conductors like voltage can and is only the original source of the electrical energy with no circuitry?

[willnonya]

I know 'gate-keeping' is the Boogeyman de jour but when attempting to communicate scientific ideas to a scientific audience it helps to have the proper vocabulary.

It is much the same as your teachers not being able to bridge the gap between concepts you understand and those needed to understand EMF and PD.

[sp332]

Or that other people didn't know what he was talking about.