Peter T. Daniels ran out of electrical outlets; states rewiring entire house to be the only feasible solution.
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From: jimp on 29 Mar 2010 14:06 In sci.physics Doctroid <doctroid(a)mailinator.com> wrote: > In article <hoql5j$rn5$1(a)news.albasani.net>, > "Skitt" <skitt99(a)comcast.net> wrote: > >> Doctroid wrote: >> > Peter Moylan wrote: >> >> PaulJK wrote: >> >>> Doctroid wrote: >> >>>> "PaulJK" wrote: >> >> >>>>> Voltage and current are proportional to each other. >> >>>>> It is therefore sufficient to say that damage is proportional >> >>>>> to one of them. >> >>>> Only in materials and voltage/current ranges where Ohm's "law" is >> >>>> obeyed. And if damage is occurring, it probably isn't. >> >>> >> >>> Ohm's law is always obeyed in all aparatus made by humans. >> >>> >> >> Except when it isn't - which is most of the time. >> >> >> >> It's true that a great many resistors are nearly linear, i.e. they >> >> can be said to obey Ohm's law to a reasonable degree of accuracy, >> >> provided that you don't go beyond their design limits. >> >> >> >> It's equally true that some resistive devices are *deliberately* >> >> made to be nonlinear. A semiconductor diode, for example, would be >> >> totally useless if it obeyed Ohm's law. >> > >> > Besides which, the subject under discussion was not human-made >> > apparatus, but humans. >> > >> > And again, under conditions where the electric current is causing >> > tissue damage, Ohm's "law" doesn't really apply. >> >> Ohms law applies quite well. It is the encountered resistance that is >> changing as the skin (of much higher resistance than the mushy and moist >> innards) is damaged. > > Your argument is circular. If you define "resistance" as the ratio of > voltage to current, possibly varying with time, voltage, or current, > then sure, Ohm's Law works; but then Ohm's Law becomes a tautology, > trivially satisfied by everything and predicting nothing. The "law" is > a useful law only in circumstances where voltage and current do not > alter the electrical properties of the material; then it becomes an > observation that current is proportional to voltage for all voltages and > currents within some large range of applicability. That observation is > not valid for the situation described here. Nonsense. All things obey Ohm's law exactly because R=V/I is the definition of resistance. Obviously you've never heard of the terms active device, load line, or operating point. -- Jim Pennino Remove .spam.sux to reply.
From: Otto Bahn on 29 Mar 2010 14:36 "Adam Funk" <a24061(a)ducksburg.com> wrote >> If that is so, then please tell me how you define "resistance". > > It's futile, Doctroid. What's impeding it? --oTTo--
From: Doctroid on 29 Mar 2010 14:36 In article <nq6787-qkc.ln1(a)mail.specsol.com>, jimp(a)specsol.spam.sux.com wrote: > All things obey Ohm's law exactly because R=V/I is the definition of > resistance. In that case I hereby announce Doctroid's Law which states that V = D * C where V is the electrical potential across a device, and C is the total mass of chocolate consumed in the past year by the person who measures V. D is the device's Doctroidance, which is in fact defined by D = V / C, and of course is not constant. Therefore Doctroid's law always holds for all circumstances. It is also perfectly useless. As is Ohm's Law, if you consider it to be solely a definition of resistance: it has no predictive power. -- Sig available on request. - Doctroid
From: Doctroid on 29 Mar 2010 14:39 In article <hoqotv$2cu$1(a)news.albasani.net>, "Skitt" <skitt99(a)comcast.net> wrote: > Doctroid wrote: > > "Skitt" wrote: > >> Doctroid wrote: > >>> "Skitt" wrote: > >>>> Doctroid wrote: > >>>>> Peter Moylan wrote: > >>>>>> PaulJK wrote: > >>>>>>> Doctroid wrote: > >>>>>>>> "PaulJK" wrote: > > >>>>>>>>> Voltage and current are proportional to each other. > >>>>>>>>> It is therefore sufficient to say that damage is proportional > >>>>>>>>> to one of them. > >>>>>>>> Only in materials and voltage/current ranges where Ohm's "law" > >>>>>>>> is obeyed. And if damage is occurring, it probably isn't. > >>>>>>> > >>>>>>> Ohm's law is always obeyed in all aparatus made by humans. > >>>>>>> > >>>>>> Except when it isn't - which is most of the time. > >>>>>> > >>>>>> It's true that a great many resistors are nearly linear, i.e. > >>>>>> they can be said to obey Ohm's law to a reasonable degree of > >>>>>> accuracy, provided that you don't go beyond their design limits. > >>>>>> > >>>>>> It's equally true that some resistive devices are *deliberately* > >>>>>> made to be nonlinear. A semiconductor diode, for example, would > >>>>>> be totally useless if it obeyed Ohm's law. > >>>>> > >>>>> Besides which, the subject under discussion was not human-made > >>>>> apparatus, but humans. > >>>>> > >>>>> And again, under conditions where the electric current is causing > >>>>> tissue damage, Ohm's "law" doesn't really apply. > >>>> > >>>> Ohms law applies quite well. It is the encountered resistance that > >>>> is changing as the skin (of much higher resistance than the mushy > >>>> and moist innards) is damaged. > >>> > >>> Your argument is circular. If you define "resistance" as the ratio > >>> of voltage to current, possibly varying with time, voltage, or > >>> current, then sure, Ohm's Law works; but then Ohm's Law becomes a > >>> tautology, trivially satisfied by everything and predicting > >>> nothing. The "law" is a useful law only in circumstances where > >>> voltage and current do not alter the electrical properties of the > >>> material; then it becomes an observation that current is > >>> proportional to voltage for all voltages and currents within some > >>> large range of applicability. That observation is not valid for the > >>> situation described here. > >> > >> Ohm's law describes the relationship between electrical current, > >> resistance, and potential in a circuit. That's it. Any member of > >> that circuit can vary at any given time and place, but the defined > >> relationship remains intact, forcing a change in another member. > > > > If that is so, then please tell me how you define "resistance". > > Resistance is the opposition offered by a body or substance to the passage > through it of an electric current. Quantitative definition, please, not just a description. Here is a 1N4002 diode: How would you determine its resistance? -- Sig available on request. - Doctroid
From: Skitt on 29 Mar 2010 14:52
Doctroid wrote: > "Skitt" wrote: >> Doctroid wrote: >>> "Skitt" wrote: >>>> Doctroid wrote: >>>>> "Skitt" wrote: >>>>>> Doctroid wrote: >>>>>>> Peter Moylan wrote: >>>>>>>> PaulJK wrote: >>>>>>>>> Doctroid wrote: >>>>>>>>>> "PaulJK" wrote: >>>>>>>>>>> Voltage and current are proportional to each other. >>>>>>>>>>> It is therefore sufficient to say that damage is >>>>>>>>>>> proportional to one of them. >>>>>>>>>> Only in materials and voltage/current ranges where Ohm's >>>>>>>>>> "law" is obeyed. And if damage is occurring, it probably >>>>>>>>>> isn't. >>>>>>>>> >>>>>>>>> Ohm's law is always obeyed in all aparatus made by humans. >>>>>>>>> >>>>>>>> Except when it isn't - which is most of the time. >>>>>>>> >>>>>>>> It's true that a great many resistors are nearly linear, i.e. >>>>>>>> they can be said to obey Ohm's law to a reasonable degree of >>>>>>>> accuracy, provided that you don't go beyond their design >>>>>>>> limits. >>>>>>>> >>>>>>>> It's equally true that some resistive devices are >>>>>>>> *deliberately* made to be nonlinear. A semiconductor diode, >>>>>>>> for example, would be totally useless if it obeyed Ohm's law. >>>>>>> >>>>>>> Besides which, the subject under discussion was not human-made >>>>>>> apparatus, but humans. >>>>>>> >>>>>>> And again, under conditions where the electric current is >>>>>>> causing tissue damage, Ohm's "law" doesn't really apply. >>>>>> >>>>>> Ohms law applies quite well. It is the encountered resistance >>>>>> that is changing as the skin (of much higher resistance than the >>>>>> mushy and moist innards) is damaged. >>>>> >>>>> Your argument is circular. If you define "resistance" as the ratio >>>>> of voltage to current, possibly varying with time, voltage, or >>>>> current, then sure, Ohm's Law works; but then Ohm's Law becomes a >>>>> tautology, trivially satisfied by everything and predicting >>>>> nothing. The "law" is a useful law only in circumstances where >>>>> voltage and current do not alter the electrical properties of the >>>>> material; then it becomes an observation that current is >>>>> proportional to voltage for all voltages and currents within some >>>>> large range of applicability. That observation is not valid for >>>>> the situation described here. >>>> >>>> Ohm's law describes the relationship between electrical current, >>>> resistance, and potential in a circuit. That's it. Any member of >>>> that circuit can vary at any given time and place, but the defined >>>> relationship remains intact, forcing a change in another member. >>> >>> If that is so, then please tell me how you define "resistance". >> >> Resistance is the opposition offered by a body or substance to the >> passage through it of an electric current. > > Quantitative definition, please, not just a description. Here is a > 1N4002 diode: How would you determine its resistance? Ohm's Law does not provide a "quantitative definition". As I said, it describes a relationship. When values of two of the variables are provided, the value of the third can be obtained. -- Skitt (in SF Bay Area) http://home.comcast.net/~skitt99/main.html |