trader_4 pretended :
On Monday, May 30, 2016 at 2:18:37 PM UTC-4, FromTheRafters wrote:


Think of it this way:

Distance equals rate times time (D=RT) and you have two trains on a
railroad track. Detroit to Chicago on one end and Chicago to Detroit on
the other. Neither train is moving. Does the distance between them drop
to zero?

No, it doesn't.


The distance in your formula is not the distance between the cities,
which of course is constant and never changes. The distance in
your formula is the distance THE TRAIN TRAVELS.




Voltage drop has no meaning in an 'open circuit', which isn't actually
a circuit at all, just as 'rate' has no meaning for objects which
aren't moving.


From Wikipedia:

"An electronic circuit is composed of individual electronic components,
such as resistors, transistors, capacitors, inductors and diodes,
connected by conductive wires or traces through which electric current
can flow."

If current can't flow, it stands to reason that it is not a circuit,
and 'voltage drop' has no meaning.

It does have meaning, it's ZERO. Zero in physics has meaning. It can
be measured. The voltage on the ends of that 100 ft of wire is exactly
the same.,

No argument on that point.

because the voltage drop across the wire with no current
flowing is zero.

There is no such thing as a 'voltage drop' when there is no current
flowing.


Which is exactly the same thing as saying the voltage drop is zero.
It's like saying if we have 3 apples and take 3 away, how many are
there now? The answer of course is ZERO, but what you're arguing
is that ZERO has no meaning. It does with apples and it does with
regard to Ohm's Law and a voltage drop of zero with no current.



https://www.youtube.com/watch?v=ggKnH-95ty0

It's like saying a velocity of zero has no meaning.

D=RT, so when the rate (velocity) is zero then D=zero*T and since
zero*T equals zero then D equals zero, so you are saying that the
distance is zero. This is obviously not the case.


Say what now? Distance Traveled= Rate x Time. If the rate is zero,
then the distance traveled is zero. Again, clearly zero has meaning.

Not if you use the D=RT formula, it is 'undefined' when either R or T
is zero (I did *not* say approaching zero).

https://en.wikipedia.org/wiki/Division_by_zero

Consider this:

What is the amperage (A) when you put zero ohms (R) resistance across
an ideal 12 volt (V) source?

Answer:

Undefined! Because A=V/R and you can't divide by zero.


Poor attempt at diversion.
But we're not dividing by zero in the case of Ohm's Law, nor in
your example of motion above. And from a math, physics and engineering
perspective what happens in your new example is that as the resistance
approaches zero, the current approaches infinity. We deal with infinity and
things approaching limits in engineering and math. It's not a mystery. But
none of this has anything to do with what we are doing with Ohm's Law,
because the voltage drop does not involve dividing by zero.

That is true, unless you state that I or R is zero. See above and
below.

This is simple math, why are you struggling with it?


Look, now you're going to start taking cheap shots? Tthe only one
here who was obviously struggling is Diesel. He
doesn't understand Ohm's Law. But now we can add you to the list because
you can't understand that in the simple case of distance = rate * time,
a zero rate gives an answer of ZERO distance traveled and that answer
of zero definitely has meaning, just like zero voltage drop from Ohm's Law
has meaning.

Simple math, you are *not* allowed to divide by zero - it is
*undefined*. Infinity is okay to work with because things in that
formula can be infinitely small or infinitely large.

Gfre, WTF has happened to education in America? We now have two idiots here
trying to explain basic math and electricity to us and neither knows
WTF they are talking about.

E=IR
I=E/R
R=E/I

If you state that either I or R is zero (as is the case with open
circuit, which is not really a circuit, or zero resistance attached to
an ideal source) the formula doesn't work. There was mention of "zero"
current and in the 'superconductor' comment was about zero resistance.
My analogy with the trains was a bit of fun, but still illustrates that
dividing by zero yields the result of 'undefined' *not* 'zero'.

I, of course, agree about 'approaching' these limits as being worthy of
consideration. However, that was *not* what I was replying to.

Also, there is no such thing as 'voltage drop' when there is no current
because 'voltage drop' is defined by there being current. You can have
voltage drop across a fuse just before it blows, but the voltage there
after it blows is not 'voltage drop' because there is no current.