Inverse of power - Page 1
Forum section: electronics / general

author: Vtile
author_rank: Super Contributor
timestamp: August 09, 2017, 02:59:28 pm
content: Hey, just popped to my mind does anyone know if inverse of power have given a special nameas admittance etc. conducting plane terminology which Heaviside did name...Edit..As we commonly use potential or voltage plane to do our calculations, but some gray bearded wise man have some point of time invented that if we apply inverse for resistance our calculations comes much easier for a parallel resistances. Then the invention were given a name conductance (or admittance in AC analysis). That prompted my question is there a name given for 1/W an inverse of power.. The ones who doesn't know it makes series power in calculations sum up like conductances in parallel.

author: Zero999
author_rank: Super Contributor
timestamp: August 09, 2017, 03:26:27 pm
content: Quote from: Vtile on August 09, 2017, 02:59:28 pmI don't understand the question. What do you mean by the inverse of power?

author: Benta
author_rank: Super Contributor
timestamp: August 09, 2017, 04:18:49 pm
content: It's related to the inverse of voltage and current.Also named:unvoltageuncurrentunpower

author: alsetalokin4017
author_rank: Super Contributor
timestamp: August 09, 2017, 04:40:15 pm
content: Well, power is measured in Watts, which are Joules per Second. So the inverse would be Seconds per Joule, or Sttaw.

author: tronde
author_rank: Frequent Contributor
timestamp: August 09, 2017, 04:44:15 pm
content: Quote from: Hero999 on August 09, 2017, 03:26:27 pmI think he mean that since the inverse of conductance is resistance, he wonders if there is something like that for power as well.

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 09, 2017, 05:16:34 pm
content: Quote from: alsetalokin4017 on August 09, 2017, 04:40:15 pmIndeed!I'm old enough to remember that conductance units were "mohs", ohms spelled backwards.On that same venue, then the inverse reactive power would be RAV?

author: WastelandTek
author_rank: Frequent Contributor
timestamp: August 09, 2017, 05:21:32 pm
content: yeah, its called "one over power"

author: Vtile
author_rank: Super Contributor
timestamp: August 09, 2017, 05:22:33 pm
content: Quote from: tronde on August 09, 2017, 04:44:15 pmYep. Is there a naming convention for it. I know that if it does have or have had one, it is not used now, but I thought if someone have heard it as an amusing side note in some academic courses. The guestion is serious.LesPower

author: Zero999
author_rank: Super Contributor
timestamp: August 09, 2017, 05:49:34 pm
content: Quote from: Vtile on August 09, 2017, 05:22:33 pmNotice how there is no inverse of voltage or current? It's because it doesn't make any sense.Resistance and conductance are physical properties of a substance. Voltage and current describe the potential difference and the number of charge carries flowing in a circuit. Power is the amount of energy dissipated per second.

author: Vtile
author_rank: Super Contributor
timestamp: August 09, 2017, 07:42:53 pm
content: Oh, well I tried to ask, maybe I should have put this on the general chat or technical discussion instead.I'm partly offended from the "doesn't make any sense" since it would make a lot of sense when using conductance. If you try to think what it truely means instead of being unpolite and ingnorant you notice that there certainly is inverse insomelevel of all three. P=G*U^2

author: Ratch
author_rank: Regular Contributor
timestamp: August 09, 2017, 08:07:56 pm
content: It would not change things. Some physical quantities can be defined as inverses of each other. Others cannot. What would be the inverses of length, area, volume, force, energy, etc? The list is endless.Ratch

author: Vtile
author_rank: Super Contributor
timestamp: August 09, 2017, 08:19:36 pm
content: Quote from: Ratch on August 09, 2017, 08:07:56 pmIndeed the list is endless, none are going to change the power to some odd antienergy thing. I did just ask if there happens to be a name (obsolete or not) for the mathematical reciprocal of power.

author: Vtile
author_rank: Super Contributor
timestamp: August 09, 2017, 10:11:24 pm
content: ok. sorry I did loose my temper a bit. I'm just looking if there would have been a term to use in my notation (and just for interest). There is these historical terms that were in use before electromagnetism were integrated to SI system. mksa and Giorgi system and what all there were.I will use (in my private notes) inverse of P which is b as Blockance (with my less than perfect english it makes sense) as noted time to dissipate Joule of energy.Oh, actually d since B were already reserved for susceptance.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: August 09, 2017, 10:27:56 pm
content: Power is energy flow. Joules per second. The inverse would be seconds per joule. That could apply in a case like determining how long it takes to charge a camera flash capacitor, I guess. It isn't usual to talk in such terms though. Why not? Just, convention.

author: alm
author_rank: Super Contributor
timestamp: August 09, 2017, 10:41:01 pm
content: There are also not many common formulas involving sums of 1/P, which is one of the reasons why conductance/admittance/susceptance enjoy some popularity.

author: cdev
author_rank: Super Contributor
timestamp: August 09, 2017, 10:46:25 pm
content: DARK ENERGY....https://www.newscientist.com/article/2143103-new-sky-survey-shows-that-dark-energy-may-one-day-tear-us-apart/

author: IanB
author_rank: Super Contributor
timestamp: August 09, 2017, 10:50:31 pm
content: Power has dimensions of energy per time. It is a rate. For instance 10 W means 10 joules per second.The inverse of power has dimensions of time per unit of energy. It is a measure of how fast energy can be transferred. For example, 10 W can also mean 1/10 second per joule. The smaller the time the faster the energy transfer, so 1/50 second per joule would be 50 W.Although this concept makes some sense theoretically, I don't know of any cases where it has a practical use.

author: Benta
author_rank: Super Contributor
timestamp: August 09, 2017, 11:03:56 pm
content: QuoteMathematically, you can do whatever you want. If you want to make a set of definitions like:1/U = dodo1/I = mojo1/P = gonzoIn that world, you'd have for instance: mojo/dodo = RHow useful that is... I don't know.But in the end, you'll have to translate it to U, I or P anyway.

author: Vtile
author_rank: Super Contributor
timestamp: August 09, 2017, 11:22:59 pm
content: Nah. don't pull it to total joke. If you put indascent lamps in series easiest way is to use conductance domain to calculate 1(P1^-1 + P2^-1) more easy would to write 1/(d1+d2...dn) in other words it is needed for jumping back and forth between resistance and conductance domain.Watt - W - M - Momentance much more meaningfull and iirc M is free. As good as u anything else atleast easy to remember.

author: Cubdriver
author_rank: Unknown
timestamp: August 10, 2017, 03:13:31 am
content: I can't see how such a thing could work for power.Resistance and conductance are simply the same property viewed from two opposite perspectives. Resistance is opposition to the flow of current, whereas conductance is ease of current flow. It's the same thing, but with different reference points. Think of a glass partially filled with water. Resistance might be how full it is, as measured from the bottom. Conductance would be how empty it is, as measured from the top. Obviously they're the opposite of one another - 0.25 full = 0.75 empty.In the case of things like resistors, the math is easier using resistance when they're in series, as the resistances are cumulative and add together to give the total. In parallel, as the ease of current flow adds due to the parallel paths combining to allow more current to flow; in this instance it's much easier to add the conductances then convert back to resistance. To try to make a rough correlation to the partially filled glasses I used as a reference example above, if you wanted to know the total amount of water all the glasses contained, my 'resistance' measurement would be better, as you'd add the amounts to get the total. If you wanted to know how much more water you could add, then the 'conductance' would be easier as again it would be a simple addition, but of the empty space this time. To calculate it using the 'resistance', you'd have to tally the 'resistance' and the total capacity, then subtract the 'resistance' from the capacity to get the 'conductance'.Hopefully this makes some sense....-Pat

author: Zero999
author_rank: Super Contributor
timestamp: August 10, 2017, 08:27:24 am
content: Quote from: Vtile on August 09, 2017, 07:42:53 pmNo offence was intended.Resistance can be inverse because it's the ratio of voltage to current, through a load. For example, in a 1 Ohm load, the voltage will be equal to the current, whilst in a two Ohm load, you'll get 2V, per Amp and so on. Conductance is the the ratio of current to voltage, so for a 1 siemen load you'll get 1A per V, for a 2 siemen load you'll have 2A per V and so on.

author: gregariz
author_rank: Frequent Contributor
timestamp: August 10, 2017, 09:05:25 am
content: The inverse of Power would be Loss.I don't think a closed form solution is necessarily simple, for example if P = (V^2)/R then Loss would be R/(V^2).For those with a physics/electromagnetics bent that equation looks suspiciously like a decay component of Attenuation. If I had to guess I would say that is because common circuit theory/equations are essentially approximate solution from first principles, not exact time variant solutions.

author: Vtile
author_rank: Super Contributor
timestamp: August 10, 2017, 09:28:20 am
content: I think that loss is more of an power in different view point. Ie. heat over specified resistor can be both loss and power in exactly same circuit, only if the heat dissipation is wanted or unwanted feature it is loss or power, while it is always power in analytical sense. The mathematical reciprocal of power is only a mathematical (or thinking) tool, not much actual physical thing (while it does indeed have that seconds per Joule meaning). I'm not actually not sure no more if inverse and reciprocal have totally different meanings (philosophical) in english, in mathematical (or programming) standpoint they are the same.The models are indeed only a models! Try to calculate your workbench parasitics with it.. Victorian era model (aka centralised circuit model) and its shortcomings are obvious in microwave electronics and long distance (>50..250km depending the source) power transmissions (<100Hz).The whole thing on inverse of power is that the voltage and current act in differently in conductance domain (which I think is also known as current domain) (kind of we speak time- and s-domain reciprocals of each other), don't blame me blame heaviside.So you need different view point of the thing and use a bit conversion. If you derive the rulebase for conductance-domain circuit analysis [haven't seen it anywhere as a whole, which obviously doesn't mean that in wouldn't exist in some book somewhere] (as R-domain, but everything is done in G-domain) from the 1/R at first you are like "what in earth", but when you sleep on it, all makes sense and clarify many of the margin notes in circuit theory books.Attenuation part is interesting and rings some bells. I need to dig deeper to g-domain, now I'm barely at the doorway, while I aproximately know what happens R vs. G domain.

author: Zero999
author_rank: Super Contributor
timestamp: August 10, 2017, 10:35:50 am
content: Loss is the inverse of gain, not power. It's used when designing attenuators or when determining the power lost in a transmission line. Again, the fact that gain and loss are ratiometric measurements is the key to why they are useful.

author: IanB
author_rank: Super Contributor
timestamp: August 10, 2017, 02:02:04 pm
content: Quote from: Vtile on August 10, 2017, 09:28:20 amYou keep talking about "conductance domain", as if there is such a thing (there isn't). Also you previously said there is no such thing as KCL or KVL in "conductance domain", but of course there is. Those laws are universal, they don't depend on what nomenclature you use.Also, I notice you keep editing your earlier posts in the thread and changing your words. This makes it impossible to follow the thread since it is like shifting sands. If you want people to engage with you, please don't do that.

author: Vtile
author_rank: Super Contributor
timestamp: August 10, 2017, 03:05:25 pm
content: Quote from: IanB on August 10, 2017, 02:02:04 pmYes they act differently in analysis perspective, see belowQuote from: IanB on August 10, 2017, 02:02:04 pmNo I didn't claim that the KCL or KVL doesn't exist on "conductance domain", but I did say something like they do not exist in a way we are accustomed. The reason I removed it were that the claim is so bold and KVL and KCL are so central laws. I had no attention to pull these out at all (partly because I would make sure my logic is solid and shouldn't have any logic flaws or it this topic will be troll fest to ad nauseam), put the topic lives its own live. If we compare the KCL and KVL in these two "domains" or "planes", what ever you want to call the circuit models, the laws stay the same, but the object of the law (potential or current) will be swapped. KCL handless voltage and KVL current. This is pretty obvious when you look the parallel resistors and how we use conductance to calculate the equivalent of them.The conductance domain is only model or an visualisation of the domain that conductance and the "law of conductance (I=G*U)" will form, if applied rigorously and R-domain circuit is converted to G-domain. I'm visual thinker so I like the less-abstract visual modeling.Quote from: IanB on August 10, 2017, 02:02:04 pmYes, I tried to clarify some posts late yesterday evening as the subject is a bit odd , some would even say controversial. The KCL/KVL edit. were only one where I removed something.

author: alm
author_rank: Super Contributor
timestamp: August 10, 2017, 04:11:17 pm
content: How would the analysis of a parallel resistor circuit be any different in your 'conductance domain'? You would still figure out the voltage across the resistors from KVL (assuming it is fed from a voltage source), and subsequently determine the current through each resistor using a (modified) Ohm's law (V/R or VG). Then through KCL you can sum up the currents and use that to figure out substitution resistance/conductance. The only difference is that you use multiplications instead of divisions, which makes the math a bit easier.

author: Vtile
author_rank: Super Contributor
timestamp: August 10, 2017, 04:46:53 pm
content: Like I wrote before I have only a few days though of this so I'm not formed a picture of it as a whole and I haven't gone to admittance at all, while exposure to admittance calculus is one key reasons I have had interest of this, but not only a few days ago Trondes series of posts or article (of simplified mains network analysis) and trying to figure out the current transformer fed circuit trickered my interest again. That said.The trick is that in our parallel series resistor case they all share the same potential difference as KVL shows us. When you convert them to conductance and draw the circuit again based on addition of series resistors you end up conclusion that what is shown as parallel with resistors (r-domain) is in series with conductance representation and other way around. I haven't put too much true analysis of sources, but if we apply the series and parallel principle they also swap. Same logic also works with power.Nothing new, maybe just viewpoint.

author: IanB
author_rank: Super Contributor
timestamp: August 10, 2017, 05:52:56 pm
content: Quote from: Vtile on August 10, 2017, 04:46:53 pmIf you only have a few days of learning about these subjects it is really much too soon to be formulating these arguments. Even as a student you should expect to spend months or years developing an understanding.QuoteNo, this isn't true. The resistors are in parallel because this is the physical topology. They remain in parallel even if you use conductances instead of resistances to describe the voltage/current relationship. The arithmetic changes to addition of conductances, but that does not change the topology.

author: ebastler
author_rank: Super Contributor
timestamp: August 10, 2017, 06:25:18 pm
content: To get back to the original question, the inverse of power would be "sloth", I think.Time required per work done, measured in s/J.

author: Zero999
author_rank: Super Contributor
timestamp: August 10, 2017, 06:26:30 pm
content: Quote from: ebastler on August 10, 2017, 06:25:18 pmNah, the inverse of power is rewop.

author: Vtile
author_rank: Super Contributor
timestamp: August 11, 2017, 01:21:01 pm
content: Quote from: IanB on August 10, 2017, 05:52:56 pmSo what happens in the Thevenin-Norton Equivalent circuits aka source transformation where only one of the sources represents directly a real world and the topology do chance when applied. Note that you should explain this analytical transformation trick now with physical topology.

author: Brumby
author_rank: Unknown
timestamp: August 11, 2017, 04:45:34 pm
content: Why is it that I am caught on the fact that with that transformation, you are changing the type of power sourceANDthe placement of the resistor...?

author: Vtile
author_rank: Super Contributor
timestamp: August 11, 2017, 05:25:24 pm
content: To keep it conpatible to regular model obviously and because of the ideal source properties there needs to be those components there to fullfill the route and division of power...OK, need to get another Aspirin, can't think straight.