Do you think an LED is a resistor?

[Sredni]

We name things by their dominant property.
That's why we do not call diodes, capacitors, and inductors, resistors.   

The property being...?
Diodance?

Close. It's called rectification. Diodes are also called rectifiers. That's it's dominant property and one of it's main use cases. Hence we don't call them resistors.

What are the physical units of this "rectification"?

I use resistance and it is expressed in ohms. I can tell you exactly how many ohms a silicon diode 1N4148 exhibits at a given voltage or current.

I should remind you that in circuit theory there are only four types of (passive) elements, each one described quantitatively by their respective property:

1. Resistance
2. Capacitance
3. Inductance
4. Memristance

Do you think there is a fifth one, rectification or rectificance?

[MK14]

What are the physical units of this "rectification"?

I use resistance and it is expressed in ohms. I can tell you exactly how many ohms a silicon diode 1N4148 exhibits at a given voltage or current.

I should remind you that in circuit theory there are only four types of (passive) elements, each one described quantitatively by their respective property:

1. Resistance
2. Capacitance
3. Inductance
4. Memristance

Do you think there is a fifth one, rectification or rectificance?

What exactly is your equivalent circuit for a diode (such as the 1N4148, you mentioned)?

Let's put it in a black box, and let an independent observer, see if they can tell your equivalent circuit, from another black box, containing a real diode.

Inspiration for this post, came from here:
https://www.sciencedirect.com/topics/engineering/circuit-theory

[PlainName]

I don't know how to say it more clearly.

I think if you look just two message up your problem will be solved.

[madires]

As an academic exercise one could model an LED as a strange kind of resistor. But there's more. An LED can be used as a poor light sensor. So one could have the idea to model an LED as a current or voltage source. And we could model a power source as a negative resistance. Now the LED's resistance model becomes even more complex. But does this make an LED a power source, a resistor, or something else?

[Berni]

And what a diode with negligible capacitance does is... showing a resistance (which is not constant but depends on the voltage or current). That is all it does, from the point of view of the circuit. It does not matter that the power it takes out goes all in IR heat, visible light or aura vibrations. The circuit sees a variable resistance (a fixed resistance once you fixed the operating point).

And yet people cannot see it is behaving as a resistor. I find it fascinating. (I have just watched an old ST convention on YT so I'm in Spock mode, now).

(Funny that nobody has noticed I called a varicap a nonlinear capacitor...)

The problem is that you are just mixing together commonly used terms as if it was one thing. There is a reason why these things are called different things.

What you are trying to say is that a diode exhibits the effect of "electrical resistance" or "resistivity".

This effect is not particularly special and just describes that the device can consume electrical power and turn it into something else, rather than store it and give it back(like capacitance or inductance can). The most common example of this is indeed a resistor that turns the applied power into heat, but other devices can turn it into other things, like a LED can turn it straight into light, an electrolysis cell can turn it into chemical energy..etc. The laws of physics impose this as a requirement since energy can only be moved or converted. This is why the effect of resistivity is everywhere in electrical circuits. Any DC circuit can only be comprised of power sources and resistances to extract work from said sources (Yes even a memristor becomes just a regular resistor once observed in steady state DC conditions). This in itself is pretty neat.

A resistor is 2 terminal electrical device that primarily exhibits the effect of electrical resistance. From wikipedia the first line reads "A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element" Such components are expected to have predictable and well controlled resistance, since the ones that don't are given different names, this is to distinguish them and avoid confusion. For example a resistor where its resistance is strongly affected by the voltage across it is called a varistor or "voltage dependent resistor". So if you are to draw similarities, you can say a diode is a form of asymmetrical varistor.

In a similar vein a varicap diode is still just a PN junction diode. It has the same type of "varistor like" behavior as a regular rectifier diode. So why does it need a different name then? It is just because it is specifically optimized to implement the effect voltage dependent capacitance, so the name already tells you about what characteristics to expect from the component.

But bending the meaning of common industry standard terms helps nobody. It just causes confusion and misunderstanding.

[magic]

An ideal diode is a nonlinear resistor whose vi characteristic is a piecewise function formed by an horizontal line until V=0 and a vertical line for V=0.
It is a resistor that has infinite resistance (the horizontal part of the vi char) for V<0 and zero resistance for V>=0.

If only William Shockley could realize it's that simple and spare us those bizarre exponential equations...

[Gyro]

It's quicker to draw the schematic, but specifying some of the values is very tricky (and sample dependent) and the parasitics are absolutely horrendous.  

[Zero999]

We name things by their dominant property.
That's why we do not call diodes, capacitors, and inductors, resistors.   

The property being...?
Diodance?

Close. It's called rectification. Diodes are also called rectifiers. That's it's dominant property and one of it's main use cases. Hence we don't call them resistors.

What are the physical units of this "rectification"?

I use resistance and it is expressed in ohms. I can tell you exactly how many ohms a silicon diode 1N4148 exhibits at a given voltage or current.

I should remind you that in circuit theory there are only four types of (passive) elements, each one described quantitatively by their respective property:

1. Resistance
2. Capacitance
3. Inductance
4. Memristance

Do you think there is a fifth one, rectification or rectificance?

EDIT:

To spell it out for you:

A diode is not a passive device.

[Nominal Animal]

I can buy LEDs and resistors (of the fixed resistance kind) off Mouser, but nobody sells any "nonlinear resistors".  Are they magick?

Or is it just a stupid term used in a narrow field, because the more widely used "nonlinear component" or "nonlinear part" just didn't sit right with The Big Names?  Just like the artsy-fartsy visual arts people who redefine exact physics terms all willy-nilly, and then wonder why they find physics so unfathomably strange (until they learn that terms are specific to the field or context they are used in, and not universal).

If you want to use the narrow field definition, say so; otherwise you're just playing tricks on others.

It is okay to use field specific terms only when you make the usage clear; i.e. either define the term, for example via "(according to the definition used in electrical engineering)" or "(according to the definition used in visual arts)".  Otherwise everyone else will default to the standard dictionary definition, and think of you as a highly obnoxious person for playing word games on others like that.

The fact that Sredni acknowledged that had they defined the terms there would be no reason for the poll, tells everyone everything worth knowing.  The reason this poll was created has nothing to do with the terms or devices described by those terms, and everything to do with Sredni trying to feel superior to others by playing word games.

I find it contemptible.  It does not surprise me at all that the question initially came up in StackExchange: a site for social points-scoring masquerading as questions and answers. 

[tooki]

Let's start by looking at systemic racism and patriarchal influence in engineering. The fact that the colours brown and black in the resistor colour code indicate low values 0 and 1 and white is the highest at 9, demonstrates that resistors are racist and white supremacist. Male and female connectors are a sign of heteronormativity, which marginalizes gay and non-binary voices.

You’re right! As a gay man, I shall endeavor to only use hermaphroditic connectors in my future designs! (Since then each contact is the same as the one it mates with. Like me! 😂)

[Gyro]

Let's start by looking at systemic racism and patriarchal influence in engineering. The fact that the colours brown and black in the resistor colour code indicate low values 0 and 1 and white is the highest at 9, demonstrates that resistors are racist and white supremacist. Male and female connectors are a sign of heteronormativity, which marginalizes gay and non-binary voices.

I sense an opportunity to bring this daft thread to a close.

[Sredni]

I sense an opportunity to bring this daft thread to a close.

It looks like some people feels threatened by ideas that do not fit in the frozen model they have made of the world when they were in high school.
I have witnessed a lot of name calling in this thread, and I have chosen not to respond to any provocation (stupid idea, daft thread, silly jokes about using resistors symbols everywhere, complex of superiority...). It seems we have reached a new level: since I do not accept provocations, the reason for closing the thread is fabricated entirely by someone else.

This is interesting from a social point of view, but I intend to keep the thread firmly on technical grounds and I hope that an evential moderation would be limited to the removal of the non technical posts.

[Nominal Animal]

It looks like some people feels threatened

No, nobody is threatened by your lame attempt at tricking others so you can feel superior.  We're just exasperated.

Perhaps you should read the Why writing style and grammar matters in posts, a sticky in the Beginners forum?  Especially the paragraph about terms and abbreviations,

Because terms and abbreviations vary across the world, it is important to define the terms and abbreviations you use, to ensure your post is understood the way you intended.  For example, CIA does not always refer to an intelligence agency.  It may refer to a MOS 6526 or MOS 8520 Complex Interface Adapter IC (as used with the 6502 microprocessor), "Confidentiality, Integrity, Availability" (concept triplet in information security), CAN in automation, or a number of other things including four different international airports.  It also means that arguments like what a term exactly means (its definition) are useless, because it is just a matter of convention, and we can agree to one definition in one thread, and a different one in another thread; the important thing is that we all understand the posts the same way.

[DimitriP]

I sense an opportunity to bring this daft thread to a close.

About ^%^ time!!

[TimFox]

There is a standard term for a two-terminal device with an arbitrary relationship between the voltage and current across and through the terminals:
"One-Port" see  https://en.wikibooks.org/wiki/Circuit_Theory/One_Port_Devices 
In general, what's inside the rectangle that comprises the one-port is a bunch of more elementary devices, such as resistors, capacitors, diodes, etc., defined in a civilized manner and connected in a more-or-less complex circuit.
There's no need to re-name the one-port the "resistor", since we already have a good definition for a resistor that is far less general than what can be called a one-port.

[Sredni]

The problem is that you are just mixing together commonly used terms as if it was one thing. There is a reason why these things are called different things.

When I attended elementary school, when the dinosaurs roamed the world,  they taught me about sets. Do they still teach sets nowadays?

Because (here < stands for "include", and U stands for "union"):

Resistor < Linear resistor U Nonlinear resistor
Nonlinear resistor < incandescent lamps U diodes U ...

So, you can still call it a diode, recognize that it is a nonlinear resistor and, as such, that it belongs to the more general set of resistors.

Does this make any sense to you?

What you are trying to say is that a diode exhibits the effect of "electrical resistance" or "resistivity".

This effect is not particularly special and just describes that the device can consume electrical power and turn it into something else,

The point I make is that this is ALL a diode does.
Huge resistance when reverse biased, small resistance when forward biased. This is not a side effect. It is what it does (if we neglect secondary effects due to parasitics in real devices).
It does not store energy in the electric field.
It does not store energy in the magnetic field.
It does not do whatever sorcery a memristor does.
It just oppose a resistance that takes power out of the circuit.
 

[MK14]

The problem is that you are just mixing together commonly used terms as if it was one thing. There is a reason why these things are called different things.

When I attended elementary school, when the dinosaurs roamed the world,  they taught me about sets. Do they still teach sets nowadays?

Because (here < stands for "include", and U stands for "union"):

Resistor < Linear resistor U Nonlinear resistor
Nonlinear resistor < incandescent lamps U diodes U ...

So, you can still call it a diode, recognize that it is a nonlinear resistor and, as such, that it belongs to the more general set of resistors.

Does this make any sense to you?

What you are trying to say is that a diode exhibits the effect of "electrical resistance" or "resistivity".

This effect is not particularly special and just describes that the device can consume electrical power and turn it into something else,

The point I make is that this is ALL a diode does.
Huge resistance when reverse biased, small resistance when forward biased. This is not a side effect. It is what it does (if we neglect secondary effects due to parasitics in real devices).
It does not store energy in the electric field.
It does not store energy in the magnetic field.
It does not do whatever sorcery a memristor does.
It just oppose a resistance that takes power out of the circuit.

No, this seems to be heading into the ...
All cars are vehicles.
BUT, not all vehicles are cars.
Type of argument.

Or to use your terminology (Analogy):

Cars < Real-Cars U Toy-Cars U Pictures-of-Cars

Therefore (using your apparent logic), a toy car, is a member of 'Cars', but it is NOT, as you can't drive a toy car, between different towns etc.

A picture of a car, has some kind of connection, to a real car.  But should not be considered, as a real or usable car.  Similarly, LEDs are NOT suited to be used or classed as resistors.

Or get LEDs in a range of Ohm values between a fraction of an Ohm and many tens of megaohms.

I.e. LEDs are not usually used (or suitable for being used) as 'RESISTORS'.

[IanB]

It looks like some people feels threatened by ideas that do not fit in the frozen model they have made of the world when they were in high school.

It often turns out that when someone thinks they are smarter than everyone around them, that he or she is in fact the dumb one, and everyone around them is just raising their eyes to the heavens in amusement.

[Sredni]

It looks like some people feels threatened by ideas that do not fit in the frozen model they have made of the world when they were in high school.

It often turns out that when someone thinks they are smarter than everyone around them, that he or she is in fact the dumb one, and everyone around them is just raising their eyes to the heavens in amusement.

Anyone has the email of Leon O. Chua?

[DimitriP]

I find it contemptible.  It does not surprise me at all that the question initially came up in StackExchange:

When the fiirst post contains the phrase ""another forum" it's never a good sign.

[Sredni]

There is a standard term for a two-terminal device with an arbitrary relationship between the voltage and current across and through the terminals:
"One-Port" see  https://en.wikibooks.org/wiki/Circuit_Theory/One_Port_Devices 
In general, what's inside the rectangle that comprises the one-port is a bunch of more elementary devices, such as resistors, capacitors, diodes, etc., defined in a civilized manner and connected in a more-or-less complex circuit.
There's no need to re-name the one-port the "resistor", since we already have a good definition for a resistor that is far less general than what can be called a one-port.

Ok, so you too think that there are no nonlinear resistors. They are just one-ports. In my view, using set theory

One port < Resistor U Capacitor U Inductor U Memristor U Any circuits composed of the connection of the previous four

And then I specialize each sunset into linear and nonlinear. So to me (and to Chua, Desoer and Kuh) nonlinear resistors are a specialization of one ports, like linear resistors from which they are disjoint.

But let's switch for a second to inductors: what do you call a coil with a ferrite core? A one port (but not an inductor)? Because I guess inductor only means linear inductor, right?

[globoy]

Sredni, to answer your original question.  No, I don't think of a LED as a resistor.  Even if I accept your premise that in some abstract theoretical sense it might be considered one.  Why would I?  What useful purpose does doing so achieve?  Is it going to help me the next time I design a circuit that includes a LED?  If so, how?

And finally, why do you ask this?  To what end is your question?

[TimFox]

There is a standard term for a two-terminal device with an arbitrary relationship between the voltage and current across and through the terminals:
"One-Port" see  https://en.wikibooks.org/wiki/Circuit_Theory/One_Port_Devices 
In general, what's inside the rectangle that comprises the one-port is a bunch of more elementary devices, such as resistors, capacitors, diodes, etc., defined in a civilized manner and connected in a more-or-less complex circuit.
There's no need to re-name the one-port the "resistor", since we already have a good definition for a resistor that is far less general than what can be called a one-port.

Ok, so you too think that there are no nonlinear resistors. They are just one-ports. In my view, using set theory

One port < Resistor U Capacitor U Inductor U Memristor U Any circuits composed of the connection of the previous four

And then I specialize each sunset into linear and nonlinear. So to me (and to Chua, Desoer and Kuh) nonlinear resistors are a specialization of one ports, like linear resistors from which they are disjoint.

But let's switch for a second to inductors: what do you call a coil with a ferrite core? A one port (but not an inductor)? Because I guess inductor only means linear inductor, right?

I call it a non-linear coil.  Under reasonable limited conditions, it exhibits inductance.  In Spice, it can be modeled as a one-port that includes hysteresis.
Of course there are one-ports, encased in plastic, that can be characterized as non-linear resistors (with non-linear V vs. I equations), but extending that nomenclature to semiconductor devices is useless sophistry.

[Kim Christensen]

It is always about the resistance it opposes to the flow of current.

Yes... But it's still called a diode. I don't know how I can say that more clearly.

[switchabl]

I don't think there is anything more I can (or want) to say on the semantics argument. I just want to add one word of caution for anyone thinking of adopting the kind of mental model the OP is proposing:

There is nothing wrong mathematically with thinking of an (idealized) diode as a circuit element that has varying resistance depending on the terminal voltage. But it is important to keep in mind that a physical diode is nothing like that. It is not made from some bulk material with variable resistance, it is a semiconductor junction. Otherwise your intuition can quickly lead you astray. To give just one example, a resistor exhibits thermal noise with a spectral density of <i²> = 4k_BT/R whereas the (primary) noise mechanism in a diode is shot noise with <i²> = 2eI.