Peter T. Daniels ran out of electrical outlets; states rewiring entire house to be the only feasible solution.
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From: Peter Duncanson (BrE) on 30 Mar 2010 11:28 On Wed, 31 Mar 2010 04:03:47 +1200, "PaulJK" <paul.kriha(a)paradise.net.nz> wrote: >Peter Duncanson (BrE) wrote: >> On Tue, 30 Mar 2010 17:57:10 +1200, "PaulJK" >> <paul.kriha(a)paradise.net.nz> wrote: >> >>> >>> At every point in time and at every point inside the body >>> of a resistive conductor the Ohm's law applies with 100% >>> accuracy. It is applicable even when the conductors are >>> never completely homogeneous and never absolutely linear. >>> >>> (Excepting conditions in the super conductive environment.) >> >> That assumes that the current results from a potential difference, a >> voltage. > >Since we were originally talking about current passing through >a persons body, that was indeed an assumption I made silently. > >> If a closed circuit, a resistive ring for instance, is put in a varying >> magnetic field an induced current will flow but no potential difference >> will be created. > >If you break the circuit you will generate potential >difference between the ends of the broken loop. > >You can view the closed circuit as infinite number >of infinitely small voltage generators parallel to infinite >number of infinitely small resistances. >Each voltage generator feeds the generated current >through the rest of the loop which has a finite resistance. >From the macro point of view it looks as if no potential >differences exist. > >You be the judge if this is tongue in cheek or not. :-) > :-) -- Peter Duncanson, UK (in alt.usage.english)
From: PaulJK on 30 Mar 2010 12:57 J. Clarke wrote: > On 3/30/2010 10:27 AM, Doctroid wrote: >> In article<ebv3r55bt7v35nvejvpplqhr51dlpkklhi(a)4ax.com>, >> barbara(a)bookpro.com wrote: >> >>> On Tue, 30 Mar 2010 09:29:17 -0400, "J. Clarke" >>> <jclarke.usenet(a)cox.net> wrote: >>> >>>> On 3/30/2010 8:07 AM, Doctroid wrote: >>> >>>>> Anyone wishing to take this up with me further may write to me at >>>>> rsholmes at physics dot syr dot edu. >>>> >>>> Would you be kind enough to provide us an example of the equation that V >>>> and I follow for a material that does not obey ohm's law and tell us for >>>> what material that equation is valid? >>> >>> Oopsie, looks like you posted this accidentally to Usenet. >>> >>> BW >> >> 'sOK, I can take this one. >> >> Zener diode: >> >> http://www.reuk.co.uk/OtherImages/current-voltage-graph-zener-diode.gif Well? The semiconductors exhibit highly nonlinear relationship between voltage and their resistance resulting in nonlinear relationship between voltage and the current. However, no matter in which region of the graph you happen to be in each point in time, the Ohm's law is always perfectly applicable. The relationship between voltage, current, and resistance at each moment cannot help but conform to the law, since that's how their relationship is defined. Indirectly, you can measure the resistance at each region of the graph by the heat the diod generates. pjk > The requirement was for the equation and the material, not a link to a > Web site.
From: jimp on 30 Mar 2010 12:05 In sci.physics Doctroid <doctroid(a)mailinator.com> wrote: > In article <7uq3r59afg17p63gsvitp4qbm6uh3032f8(a)4ax.com>, > barbara(a)bookpro.com wrote: > >> On Tue, 30 Mar 2010 18:26:04 +1200, "PaulJK" >> <paul.kriha(a)paradise.net.nz> wrote: >> >> >A homework for Doctroid and P.Moylan >> >http://www.allaboutcircuits.com/worksheets/diode1.html >> > >> >just trying to help you to stop embarrassing yourself with >> >high school physics. >> >> P'raps you should ask Doctroid what he is a doctroid of. >> >> BW > > See, the thing about high school physics is, it's taught by high school > teachers out of high school textbooks to high school students. > > High school physics teachers usually do not have advanced training in > physics. Often neither do the authors of high school physics textbooks. > Even when they do, they recognize the necessity of presenting a > simplified picture to high school students, who are not ready for > differential equations, surface integrals, and deep questions about the > meaning of physical law. > > So what gets taught is "Ohm's law is V = IR". The ones who go on to > earn degrees in physics are taught there's more to it than that. (And > some of them learn it.) The ones who major in English Lit or Business > or Electrical Engineering? Might not. Since R=V/I is a definition, care to elaborate on when the relationship does not hold? Your Nobel awaits. -- Jim Pennino Remove .spam.sux to reply.
From: jimp on 30 Mar 2010 12:11 In sci.physics "Peter Duncanson (BrE)" <mail(a)peterduncanson.net> wrote: > On Tue, 30 Mar 2010 17:57:10 +1200, "PaulJK" > <paul.kriha(a)paradise.net.nz> wrote: > >> >>At every point in time and at every point inside the body >>of a resistive conductor the Ohm's law applies with 100% >>accuracy. It is applicable even when the conductors are >>never completely homogeneous and never absolutely linear. >> >>(Excepting conditions in the super conductive environment.) > > That assumes that the current results from a potential difference, a > voltage. Wrong, R=V/I is a definition. > If a closed circuit, a resistive ring for instance, is put in a varying > magnetic field an induced current will flow but no potential difference > will be created. True if, and only if, the "resistive" ring is an ideal superconductor with zero resistivity, otherwise there will be a potential difference between any two given points on the ring. -- Jim Pennino Remove .spam.sux to reply.
From: Hatunen on 30 Mar 2010 12:30
On Mon, 29 Mar 2010 10:04:26 +0100, Mike Barnes <mikebarnes(a)bluebottle.com> wrote: >jimp(a)specsol.spam.sux.com: >>The power dissipated in a resistance is a function of the resistance and >>the externally generated voltage applied to the resistance. > >Ditto. It's almost right. Batteries have internal resistance which dissipate heat by the familiar I^2R formula but the voltage is generated internally. No heat is generated in the batery unless the battery is attached to a load. The same is also true of transformers and electic motor windings. -- ************* DAVE HATUNEN (hatunen(a)cox.net) ************* * Tucson Arizona, out where the cacti grow * * My typos & mispellings are intentional copyright traps * |