aquamon
Member
http://www.electro-tech-online.com/threads/ohms-law.430/#post755773
wow, are were we really arguing about that in here?
LoL!
wow, are were we really arguing about that in here?
LoL!
Oops!That thread is almost a year old.
Nope, that's not true =) That's what just about 99.99% of all people believe though. Ohm's law only has to do with the specific case of fixed pure metal resistors at known unchanging temperatures and low currents. Ohm's law is that V=IR but his experimentation only dealt with a very very limited data set. Because experimentally the law fails under various conditions because of things like ionic flow, eddy currents inside conductors and the changing state of a materials conductance under voltage and temperature changes. The V=IR and all it's derivatives are perfectly true for a great number of things, but the equations are not actually "Ohm's law"Hero999 said:I don't see the big deal.
Ohm's law is
V = IR
V = voltage
I = current
R = resistance
No, anyone that believes that didn't actually read the original papers that Ohm wrote on the subject, I did because I was trying to prove MrAL wrong over this very same linguistic misunderstanding. Believe me, I had my foot in my mouth for a week over that one, though the arguement you bring up goes to show exactly my problem. Even though I was wrong so many people have such a misinformed understanding of what Ohm's Law actually is that in common language it has actually become more prevalent for people to be incorrect. Kind of the same way words change over time, they were used out of context so many times they garnered the new meaning.Sorry but anyone who doesn't understand that, after an hour's reading about on the topic, doesn't have the intelligence required to be an engineer.
Which again proves the point. The original paper that Ohm published that had the equations dealt ONLY with highly controlled linear loads. Non-linear loads do not obey Ohm's law, the equations that were derived from the papers that Ohm wrote are often referred to as 'the law' out of context of the original manuscript (which is available online by the way) I spent HOURS researching this. I even contacted a science professor which agreed with the details I'm ascribing to and said that anyone trying to argue about this too much was wasting their time and being petty basically. His reply really made me put my foot in my mouth =) S'a hard pill to swallow.The people arguing against Ohm's law missed the point about R varying as a function of voltage and current which is the case in non-linear loads.
Have the link still? The only version I found was in German.original manuscript (which is available online by the way) I spent HOURS researching this.
Sorry, you're wrong, the resistance of a material may be dependant on other factors but Ohm's law still applies, regardless of whether the load is linear or not, noise, eddy currents, temperature changes, semiconductor junctions all change their resistance in response to the current, environmental factors or often just randomly but Ohm's law still applies: the current and voltage are still proportional to the resistance.Ohm's law is that V=IR but his experimentation only dealt with a very very limited data set. Because experimentally the law fails under various conditions because of things like ionic flow, eddy currents inside conductors and the changing state of a materials conductance under voltage and temperature changes.
It appears you're arguing about semantics.Which again proves the point. The original paper that Ohm published that had the equations dealt ONLY with highly controlled linear loads. Non-linear loads do not obey Ohm's law, the equations that were derived from the papers that Ohm wrote are often referred to as 'the law' out of context of the original manuscript (which is available online by the way) I spent HOURS researching this. I even contacted a science professor which agreed with the details I'm ascribing to and said that anyone trying to argue about this too much was wasting their time and being petty basically. His reply really made me put my foot in my mouth =) S'a hard pill to swallow.
I haven't finished reading Dr. Ohm's journal, but so far all I can find excludes nonlinear resistances. If you have completed reading it, perhaps you can direct us to the part where he includes nonlinear effects. I wouldn't think that ignoring Dr. Ohm would be constructive.It appears you're arguing about semantics.
If you're talking about a non-linear load then of course you can't use Ohm's formula to calculate the resistance which can be used to calculate the current at different voltage because the resistance will change, which is what I think you're saying.
This doesn't mean the Ohm's law doesn't apply, it just means that R can be dependant on other factor: voltage and current being two of them.
hi,I've just looked at the attachment, sorry I'm not interested enough in the subject to read a 270 page book on it so I'm leaving the discussion.
Yes, I've read and understood that but I've learned nothing new. It doesn't mean that Ohm's law doesn't apply at all V still equals IR, it's just that the resistance of a non-linear element just changes as a function of voltage or current as I explained a few posts ago.hi,
This links section covering Linear Approximations explains the non ohmic situation.
Ohm's law - Wikipedia, the free encyclopedia