Doug Miller pretended :
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.
You got me again, what I meant was Ohm's Law is not the right tool if
you are trying to use it outside of its limitations. Within its
limitations you can do as I said. Using zero like you did in the
example is outside of its limitations.
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.
Within Ohm's Law you are right about that. There is no arrangemnt of
the terms where V is problematic as far as I'm aware. It always seems
to be in the numerator or standing alone.
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.
Outside the limitations of Ohm's Law because the current can't be zero.
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.
I wasn't posting it for the question, but for the answers.