FromTheRafters wrote in news:niklg0$kke$1
@news.albasani.net:
Doug Miller laid this down on his screen :
FromTheRafters wrote in news:nik91o$q95$1
@news.albasani.net:
[...]
I'm talking about the general case of
Ohm's Law where you can take any two known quantities and calculate the
third.
*Any* two? Really?
Voltage = 120, current = zero. Calculate resistance, please.
It can't be done, and that's my point.
What, you mean your point is that you're wrong? You just stated "you can take any two
known quantities [in Ohm's Law] and calculate the third". I just showed that's not true.
Moreover, you're missing the point here rather badly. Given V = IR, with I = 0, it's not
possible to calculate any specific value for R precisely because *any finite value*
multiplied by zero is still zero. If V = 0 and I = 0, R could be anything at all -- but that doesn't
mean that Ohm's Law doesn't work. Rather, it confirms that Ohm's Law *does* work,
because the physical representation of 0 = 0R is that no matter what the resistance is, if
there's no potential difference no current will flow.
There must be current for there
to be a 'voltage drop'.
I suppose I'd agree with that statement -- but I'm not sure you realize that there does not
have to be current for there to be a potential difference.
That is the case where I don't even need to use division by zero to
show that Ohm's Law is broken.
It's *your understanding* of Ohm's Law, and of junior high school algebra, that are broken.
When there is a non-zero voltage stipulated, and the current is
stipulated as zero, the resistance must be infinite by Ohm's law.
False. This is an impossible situation. If current is zero, then voltage *must be* zero;
conversely, if voltage is non-zero, then current and resistance must both be non-zero also.
The
result is undefined because zero times infinity is undefined.
http://electronics.stackexchange.com...olating-itself
You don't bolster your argument at all by reposting a question asked by someone as
ignorant of basic algebra as yourself, especially when you clearly failed to read and
understand the many correct explanations in the answers.