Turn Your Power Supply into an Ohmmeter - It's Free!

[Ratch]

"Mike Russell" <geigy@pacbell.net> wrote in message
news:YOXRa.577$ZI2.105@newssvr24.news.prodigy.com...

Chuck Harris wrote:
Hi Ratch,

It is not as simple as all that. E = Ri has been called "Ohm's" law
for
as far back as my reference library goes, which is 1907. I cannot
verify, but I would presume that the origin of the the alleged misuse
goes even further back.

A friend of mine took an electronics class at a local JC, and he learned
"Ohm's Three Laws": E=IR, I=E/R, and R = E/I.

And the misnomer propagates on, and on, and on .... Ratch

--

Mike Russell
http://www.curvemeister.com
http://www.zocalo.net/~mgr
http://geigy.2y.net

 

[William Hayes]

"Ratch" <Watchit@Comcast.net> wrote in message
news:NK1Sa.94625$N7.12062@sccrnsc03...

those formulas are NOT Ohm's law, and it is wrong to
call them that.
As I pointed out earlier, there is no "Ohm's law equation". I
believe
you are referring to the resistance formula R=V/I and its variations,
which
is not Ohm's law, although it is often mistakenly called that. Ohm's law
is
a property of a material as explained in

http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc

/Resistance.htm

which I posted earlier. Did you read it? Ratch

I keep getting "Can not find server - the page you are looking for is
unavailable."
send me a copy.

I'm piqued. I'd like to know why you think E=I*R is not "Ohm's Law".

William Hayes, Ph.d. E&E.

"By Trying to understand the natural world around us, we gain confidence in
our ability to determine whom to trust and what to believe about other
matters as well. Without this confidence, our decisions about social,
political, and economic matters are inevitably based entirely on the most
appealing lie that someone else dishes out to us. Our appreciation of the
noticings and discoveries of both scientists and artists therefore serves,
not only to delight us, but also to help us make more satisfactory and valid
decisions and to find better solutions for our individual and societal
problems." - Frank Oppenheimer.

 

[Ratch]

"William Hayes" <wlh56@comcast.net> wrote in message
news:UY1Sa.94927$Ph3.11524@sccrnsc04...

"Ratch" <Watchit@Comcast.net> wrote in message
news:NK1Sa.94625$N7.12062@sccrnsc03...
those formulas are NOT Ohm's law, and it is wrong to
call them that.
As I pointed out earlier, there is no "Ohm's law equation". I
believe
you are referring to the resistance formula R=V/I and its variations,
which
is not Ohm's law, although it is often mistakenly called that. Ohm's
law
is
a property of a material as explained in


http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc
/Resistance.htm
which I posted earlier. Did you read it? Ratch

I keep getting "Can not find server - the page you are looking for is
unavailable."
send me a copy.

I'm piqued. I'd like to know why you think E=I*R is not "Ohm's Law".

William Hayes, Ph.d. E&E.

My apologies, try this. I can also post a couple of snippets from two good
physics books which back up the link. Ratch
http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc/Resistance.htm
http://maxwell.byu.edu/~spencerr/websumm122/node50.html

 

[William Hayes]

"Ratch" <Watchit@Comcast.net> wrote in message
news:bc2Sa.94711$N7.12100@sccrnsc03...

I'm piqued. I'd like to know why you think E=I*R is not "Ohm's Law".
My apologies, try this. I can also post a couple of snippets from two
good
physics books which back up the link. Ratch

http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc

/Resistance.htm

http://maxwell.byu.edu/~spencerr/websumm122/node50.html

Try this :
http://voltaicpower.com/Biographies/OhmBio.htm

Pay particular attention to the part referring to George Ohm determining
that the current that flows through a wire is proportional to its cross
sectional area and inversely proportional to its length provided temperature
remains constant. This is refereed to as Ohm's Law.

In your reference you have :
His rule is "that the ratio of potential difference to the current flowing
through a conductor is constant, providing all other influences such as
temperature are kept constant."

While basically your reference is almost correct, it is not fully correct.
A more appropriate reference would have been : The potential difference of
the current flowing through the conductor is proportional to its cross
sectional area and inversely proportional to its length provided temperature
remains constant. However, this would negate the relative nonsense that
followed in your link. While you can snippet links to other references,
sit back and think about how the conductor's cross sectional area relates to
the length of the conductor verses the potential difference to allow energy
(electrons) to flow through the conductor with room temperature remaining
constant.
Once you invision it, you will have grasped Ohm's Law.

In your reference you have :
This particular formula, often written as V = IR is extremely useful. It
is often known (incorrectly) as "Ohm's Law".

Why ?

 

[Ratch]

"William Hayes" <wlh56@comcast.net> wrote in message
news:HP2Sa.96346$H17.29097@sccrnsc02...

"Ratch" <Watchit@Comcast.net> wrote in message
news:bc2Sa.94711$N7.12100@sccrnsc03...
I'm piqued. I'd like to know why you think E=I*R is not "Ohm's Law".
My apologies, try this. I can also post a couple of snippets from two
good
physics books which back up the link. Ratch


http://www.launc.tased.edu.au/online/sciences/PhysSci/done/electric/resistnc
/Resistance.htm
http://maxwell.byu.edu/~spencerr/websumm122/node50.html

Try this :
http://voltaicpower.com/Biographies/OhmBio.htm

Pay particular attention to the part referring to George Ohm determining
that the current that flows through a wire is proportional to its cross
sectional area and inversely proportional to its length provided
temperature
remains constant. This is refereed to as Ohm's Law.

Your link gives two definitions of Ohm's law. The first is the one you
refer to above, in that R=resistivity*length/area. It is a resistance
formula for a conductor with known physical dimensions and resistivity, but
it is not Ohm's law. The second definition is correct and states "Ohm's law
stated that the amount of steady current through a material is directly
proportional to the voltage across the material, for some fixed
temperature". This is correct except for the I=V/R formula which is not
Ohm's law. In other words, if the voltage doubles or triples, the current
doubles or triples. If the current in a material does not follow the
voltage in a linear fashion, it is nonohmic and does not have a straight
line on a V vs I curve. On every point on that V vs I curve, I=V/R, but
that formula is not Ohm's law. Many metals do plot a more or less straight
line and are ohmic. Semiconductors and other materials do not and are
nonohmic.

In your reference you have :
His rule is "that the ratio of potential difference to the current flowing
through a conductor is constant, providing all other influences such as
temperature are kept constant."

While basically your reference is almost correct, it is not fully correct.
A more appropriate reference would have been : The potential difference of
the current flowing through the conductor is proportional to its cross
sectional area and inversely proportional to its length provided
temperature
remains constant. However, this would negate the relative nonsense that
followed in your link. While you can snippet links to other references,
sit back and think about how the conductor's cross sectional area relates
to
the length of the conductor verses the potential difference to allow
energy
(electrons) to flow through the conductor with room temperature remaining
constant.
Once you invision it, you will have grasped Ohm's Law.

The cross section of the conductor has no bearing whatsoever on whether a
material is ohmic or not. If you have a conductor made out of a certain
material, you can plot the V vs I curve. If the curve is straight, it is
ohmic regardless what the physical dimensions are--even if the cross section
varies from point to point. If you understand that resistive linearity
property of the material, then you know Ohm's law.

In your reference you have :
This particular formula, often written as V = IR is extremely useful. It
is often known (incorrectly) as "Ohm's Law".

Why ?

Here's why.

I will first quote from a college textbook called Physics, by Halliday &
Resnick, 1967, page 780. It was written by David Halliday, Professor of
Physics, University of Pittsburgh and Robert Resnick, Professor of Physics,
Rensselaer Polytechnic Institute

-----------------------------------------------------------------------
"We stress the relationship V=I*R is NOT a statement of Ohm's law. A
conductor obeys Ohm's law only if its V vs. I curve is linear, that is, if R
is independent of V and I. The relationship R=V/I remains as the general
definition of the resistance of a conductor whether or not the conductor
obeys Ohm's law. . . . . . . . . Ohm's law is a specific property of certain
materials and is NOT a general law of electromagnetism, for example, like
Gauss's law."
-----------------------------------------------------------------------

Next a quote from another college textbook called Physics for Scientists &
Engineers, by Raymond Serway, Third Edition, 1990, page 745. It was written
by Raymond A. Serway of James Madison University

-----------------------------------------------------------------------
"A current density J and an electric field E are established in a conductor
when a potential difference is maintained across the conductor. If the
potential difference is constant, the current will also be constant. Very
often, the current density in a conductor is proportional to the electric
field in the conductor. that is J=sigma*E where sigma is called the
conductivity of the conductor. Materials that obey the above equation are
said to follow Ohm's law, named after Georg Simon Ohm (1787-1854). More
specifically, Ohm's law states that for many materials (including most
metals) the ratio of the current density and electric field is a constant,
sigma, which is independent of the electric field producing the current.
Materials that obey Ohm's law, and hence demonstrate this linear behavior
between E and J, are said to be ohmic. The electrical behavior of most
materials is quite linear for very small changes in the current.
Experimentally, one finds that not all materials have this property.
Materials that do not obey Ohm's law are said to be nonohmic. Ohm's law is
not a fundamental law of nature, but an empirical relationship valid only
for certain materials."
-----------------------------------------------------------------------

OK, what could be clearer? Ohm's law refers to the linearity between voltage
and current, not relationship between voltage, current, and resistance. Yet
the formula, V = I*R has been misnamed across countless classrooms, books
and discussions. What does your textbook or school teach?

To summarize, certain materials like conductive metals follow Ohm's law, in
that their V vs.I curve is linear. Ohm's law is a property of a material,
not a general law of nature. Other conductive entities like diode junctions
or gas discharge bulbs do not have the Ohm's law property, because their
conductivity changes depending on what voltage or current is applied,
causing their V vs. I curve to be nonlinear. In all cases, V = I*R is always
correct, but it should not be called Ohm's law.

No matter what you call V = I*R, circuits will still get designed and
analyzed, and science will still progress. In any case, be aware that V =
I*R is not Ohm's law, but the V vs. I linearity, if present, is the law.

 

[Mark Jones]

William Hayes wrote:

"Frank Bemelman" <bemelmanx@euronet.nl.invalid> wrote in
message news:3f18549d$0$28888$1b62eedf@news.euronet.nl...
Let's go all nuts and talk about ohmistance & ohmistors from
now on

Cripes, You want these guys/gals to actually learn something
??

Did I hear someone say "MHO's?" : )

 

[Chuck Harris]

Hi Ratch,

What do G. Ohm, J. Maxwell, N. Tesla, J. Watt, Coulomb, Hertz, ...
all have in common?

They were dead and buried before the various engineering and physical
societies named equations and constants in their honor.

Tesla's body of work far exceeded the study of static magnetic fields;
Watt worked on steam engines, and developed the horsepower, he knew
nothing of electricity, and the metric system; Hertz was way more than
a cycle per second; and Ohm worked on more than that one equation
for resistivity.

These men were honored by various societies for their work in the
sciences. It is quite natural that the physicists and engineers
would honor different parts of these guys lifes works.

If you ask engineers what is Ohm's law, they will say E = iR,
if you ask physicists, they will give a long boring diatribe about
bulk resistivity, and cross sectional areas. If you asked George's
wife and children, they would come up with yet another entirely
different answer.

This is not the first time engineers and physicists have differed
in their approaches to academic study. Just think of the different
meanings of E and V, i and i and j, ....

So, just as you can quote a couple of physics text books and "prove"
that ohm's law is one thing, I can quote an equal number of
engineering text books that say otherwise.

-Chuck

Ratch wrote:

No matter what you call V = I*R, circuits will still get designed and
analyzed, and science will still progress. In any case, be aware that V =
I*R is not Ohm's law, but the V vs. I linearity, if present, is the law.

 

[Watson A.Name - 'Watt Sun]

In article <Zj1Sa.94494$N7.11951@sccrnsc03>, wlh56@comcast.net
mentioned...

"Sofie" <sofie@olypen.com> wrote in message
news:vheca77sefdtd5@corp.supernews.com...
Sir Charles W. Shults III:
That is a good in depth, overly complicated, answer but not the one I was
looking for

There was these two Engineers.... leaving the work place, they were headed
home.
They left the building headed out to the parking lot when the first engineer
stopped at a brand new 10 speed bike,
bent over and unlocked it. The second engineer looked at the first and
said, "Hey, I didn't know you got a new bike."
The first engineer started recounting his experience at getting the new
bike, "Yeah, I was out jogging my 1/2 block down the street when a lady on
this ten speed bike came by. She stopped. Got off the bike. Took all her
clothes off. Stood in front of me and said to me that I could have anything
I wanted." The second engineer thought for a moment and replied, " Yeah,
good choice, I don't think you'd fit into any girlie clothes, either."

Heh-heh. I think I posted that or something similar a couple weeks
ago.

So, now that we've had a nice discussion about ohm's law, explain that
fangled volt/amps rating on stuff.
I'm sure someone will note it is "nonohmic" somewhere...

So if a regular diode is nonohmic, what's a schottky diode? Half a
nonohmic? Sort of like the sound of one hand clapping... ;-)


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Ratch]

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bfbfqe$1jt$1@bob.news.rcn.net...

Hi Ratch,

What do G. Ohm, J. Maxwell, N. Tesla, J. Watt, Coulomb, Hertz, ...
all have in common?

They were dead and buried before the various engineering and physical
societies named equations and constants in their honor.

Tesla's body of work far exceeded the study of static magnetic fields;
Watt worked on steam engines, and developed the horsepower, he knew
nothing of electricity, and the metric system; Hertz was way more than
a cycle per second; and Ohm worked on more than that one equation
for resistivity.

These men were honored by various societies for their work in the
sciences. It is quite natural that the physicists and engineers
would honor different parts of these guys lifes works.

What does the fact of receiving awards and honors posthumously have to
do with what we are discussing?

If you ask engineers what is Ohm's law, they will say E = iR,

Only because they learned it that way. If you explained the misnomer,
then what would they say?

if you ask physicists, they will give a long boring diatribe about
bulk resistivity, and cross sectional areas.

No they won't. Cross sectional areas have to do with the Resistance
formulas, not the real Ohm's law.

If you asked George's

wife and children, they would come up with yet another entirely
different answer.

Pure speculation. Was he even married? Would his family understand
the question? Would their answer have any meaning?

This is not the first time engineers and physicists have differed
in their approaches to academic study. Just think of the different
meanings of E and V, i and i and j, ....

A misnomer is not a study approach. Voltage and current have the same
meaning throughout science no matter how many different ways they are
studied or explained by representative analogs.

So, just as you can quote a couple of physics text books and "prove"
that ohm's law is one thing, I can quote an equal number of
engineering text books that say otherwise.

Those texts I quoted are really good college level textbooks. Would
the authors you would quote be able to defend their writings after being
shown what I believe is the error of their ways? Ratch

-Chuck

Ratch wrote:

No matter what you call V = I*R, circuits will still get designed and
analyzed, and science will still progress. In any case, be aware that V
=
I*R is not Ohm's law, but the V vs. I linearity, if present, is the law.

 

[Watson A.Name - 'Watt Sun]

In article <Sm1Sa.94175$ye4.66541@sccrnsc01>, wlh56@comcast.net
mentioned...

"Mark Jones" <127.0.0.1> wrote in message
newsfmdnbjnLKNyB4qiU-KYgg@buckeye-express.com...
Oh well it might have been funnier with the actual drawing. Man I need to
get out more...

I understand there are occasionally sightings of 'wild bike riding' women
when our sorts take to jogging 1/2 a block.


(I haven't tried jogging a full block ... my luck, I'd run into wild cement
truck driving women ... )

Oohh, Kinky!

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Frank Bemelman]

"Ratch" <Watchit@Comcast.net> schreef in bericht
news:xscSa.97708$Ph3.10866@sccrnsc04...

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bfbfqe$1jt$1@bob.news.rcn.net...

If you ask engineers what is Ohm's law, they will say E = iR,

Only because they learned it that way. If you explained the
misnomer,
then what would they say?

....they'd say you're a pain in the butt. You belong to the same category
as the ones that always have to say that RS232 is about voltage levels
and has nothing to do with serial ports. Strictly that is correct, but
at the the same time the *entire* world uses the term when referring
to typical serial ports such as COM1 and COM2 on your PC.

E = I * R. Ohm's Law. Always has been, and always will be.

--
Thanks,
Frank Bemelman
(remove 'x' & .invalid when sending email)

 

[Ratch]

"Frank Bemelman" <bemelmanx@euronet.nl.invalid> wrote in message
news:3f1963bf$0$28893$1b62eedf@news.euronet.nl...

"Ratch" <Watchit@Comcast.net> schreef in bericht
news:xscSa.97708$Ph3.10866@sccrnsc04...

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bfbfqe$1jt$1@bob.news.rcn.net...

If you ask engineers what is Ohm's law, they will say E = iR,

Only because they learned it that way. If you explained the
misnomer,
then what would they say?

...they'd say you're a pain in the butt. You belong to the same category
as the ones that always have to say that RS232 is about voltage levels
and has nothing to do with serial ports. Strictly that is correct, but
at the the same time the *entire* world uses the term when referring
to typical serial ports such as COM1 and COM2 on your PC.

And you would rather blame the messenger than appreciate the message.

E = I * R. Ohm's Law. Always has been, and always will be.

You are in denial. Ratch

--
Thanks,
Frank Bemelman
(remove 'x' & .invalid when sending email)

 

[Ratch]

"Costas Vlachos" <c-X-vlachos@hot-X-mail.com> wrote in message
news:bfbm5q$dls$1@hercules.btinternet.com...

Aaarghhh!!!

V = I * R

I = V / R

R = V / I

Call them what you will... When R is independent of I, I call this Ohm's
law.

Your above statement is correct.

Can we drop it now please...? Ta.

It depends on others.... Ratch

Costas

 

[Watson A.Name - 'Watt Sun]

In article <PT1Sa.94662$N7.11173@sccrnsc03>, Watchit@Comcast.net
mentioned...

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bf9642$l2a$1@bob.news.rcn.net...
[snip]

In any case, this relation has been called Ohm's law for so long, that
regardless of its origin, it *is* Ohm's law. To try and change the
common usage at this late date would just needlessly confuse the issue.

This is sort of like the SI prefix Giga. The standards publications
of NBS (now the NIST), U.S. Navy, ASME (American Society of Mechanical
Eng'rs), and others all show the pronunciation as Jiga, but people
have been mispronouncing it for so long that all hope is lost of ever
going back to the original.

And then there's the mess NIST and the international standards bodies
got us into regarding the binary prefixes (see the last two lines of
my .sig below for the URL). I've yet to hear anyone use those in a
conversation, or even in print. Just remember that 1024 kilobytes is
_not_ called a megabyte anymore!

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Costas Vlachos]

Aaarghhh!!!

V = I * R

I = V / R

R = V / I

Call them what you will... When R is independent of I, I call this Ohm's
law.

Can we drop it now please...? Ta.

Costas

 

[Chuck Harris]

Hi Ratch,

Ratch wrote:

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bfbfqe$1jt$1@bob.news.rcn.net...

Hi Ratch,

What do G. Ohm, J. Maxwell, N. Tesla, J. Watt, Coulomb, Hertz, ...
all have in common?

What does the fact of receiving awards and honors posthumously have to
do with what we are discussing?

I said nothing of awards and honors! The various scientific societies
went on a spree of naming every little thing after the giants
in the field. Torr, Tesla, Hertz, Ohm, Coulomb, Maxwell, Heisenberg,
Watt, Ampere, Curie, Voltair, and on and on and on. The things that
were named after these people were not necessarily things they had had
anything to do with.

George Ohm did NOT name this, or any other formula after himself!
That was done long after his death by fellow engineers and scientists.
It was done to honor the man. His contribution was large, so he got
a fundumental principal.

If you ask engineers what is Ohm's law, they will say E = iR,


Only because they learned it that way. If you explained the misnomer,
then what would they say?

They would say, it is not a misnomer, it is just a different equation
that is also given Ohm's name.

A misnomer is not a study approach. Voltage and current have the same
meaning throughout science no matter how many different ways they are
studied or explained by representative analogs.

You imagine that Ohm did only one thing, and that he named that thing
after himself. He did not. He did many things over his lifetime.
There is no one equation that sums up his life's work. The equations
named for Ohm were named by others long after his death. The naming
was done to honor the man for his contributions to the sciences.

So, just as you can quote a couple of physics text books and "prove"
that ohm's law is one thing, I can quote an equal number of
engineering text books that say otherwise.


Those texts I quoted are really good college level textbooks. Would
the authors you would quote be able to defend their writings after being
shown what I believe is the error of their ways? Ratch

And the texts in my library are also "really good college level
textbooks", written by prominent members of the electrical engineering
field.

Resnick is just another contemporary author of a physics book.
He is only restating what he was told, or what he believes to be true.
If you check his book out, you will find that there are no references
cited to back up his work. This is primarily because the college
text books are restatements of restatements .... It is hard to tell
where all the info originlly came from. The books are written by
professors, and professors, well, profess.

-Chuck

 

[Ratch]

Ratch wrote:
"Chuck Harris" <cfharris@erols.com> wrote in message
news:bfbfqe$1jt$1@bob.news.rcn.net...

Hi Ratch,

What do G. Ohm, J. Maxwell, N. Tesla, J. Watt, Coulomb, Hertz, ...
all have in common?

What does the fact of receiving awards and honors posthumously have
to
do with what we are discussing?

I said nothing of awards and honors! The various scientific societies
went on a spree of naming every little thing after the giants
in the field. Torr, Tesla, Hertz, Ohm, Coulomb, Maxwell, Heisenberg,
Watt, Ampere, Curie, Voltair, and on and on and on. The things that
were named after these people were not necessarily things they had had
anything to do with.

All right, I'll buy that. But if they were awarding names to physical
laws, were they not honoring the men?

George Ohm did NOT name this, or any other formula after himself!
That was done long after his death by fellow engineers and scientists.
It was done to honor the man. His contribution was large, so he got
a fundumental principal.

I will agree to that also

If you ask engineers what is Ohm's law, they will say E = iR,


Only because they learned it that way. If you explained the
misnomer,
then what would they say?

They would say, it is not a misnomer, it is just a different equation
that is also given Ohm's name.

But wrongly. Ohm's law is a property, not a equation.

A misnomer is not a study approach. Voltage and current have the
same
meaning throughout science no matter how many different ways they are
studied or explained by representative analogs.

You imagine that Ohm did only one thing, and that he named that thing
after himself. He did not. He did many things over his lifetime.
There is no one equation that sums up his life's work. The equations
named for Ohm were named by others long after his death. The naming
was done to honor the man for his contributions to the sciences.

I know that Ohm did many things, just like Newton did things other than
explain mass attraction. I maintain that
Ohm's law is named after a resistive linearity principle, and the resistance
formula V=IR is used to explain that
principle. Some people later got careless and started calling the resistance
formula Ohm's law.

So, just as you can quote a couple of physics text books and "prove"
that ohm's law is one thing, I can quote an equal number of
engineering text books that say otherwise.

Physics and mathematics are foundation sciences of
electrical/electronics engineering. If they don't agree, then EE is the one
that should change, unless it can be proved that physics is in error.
Otherwise it is the tail wagging the dog.

Those texts I quoted are really good college level textbooks.
Would
the authors you would quote be able to defend their writings after being
shown what I believe is the error of their ways? Ratch

And the texts in my library are also "really good college level
textbooks", written by prominent members of the electrical engineering
field.

I know, I have a lot of them myself. But the parts that do not follow
physics are suspect.

Resnick is just another contemporary author of a physics book.

I don't think that Prof Resnick is with us anymore.

He is only restating what he was told, or what he believes to be true.

Right, see below.

If you check his book out, you will find that there are no references
cited to back up his work.

True, it is a textbook, not a physics reference. The book already is
huge. Most textbooks don't give references because of bloat, and it becomes
subjective on how extensive they should be.

This is primarily because the college
text books are restatements of restatements .... It is hard to tell
where all the info originlly came from. The books are written by
professors, and professors, well, profess.

It is certainly true that what a professor writes is going to be what
he believes to be factual. And impossible to discern how he came upon his
knowledge. But you have to ask yourself, why did Professors Resnick and
Serway go out of their way to make a point that Ohm's law is a property of a
material and not V=IR? Does that not indicate that they looked into the
matter more closely that their contemporaries? The next time I get to a
good college library, I will look at other college physics textbooks. Ratch

 

[Franc Zabkar]

On Sat, 19 Jul 2003 09:12:20 -0700, Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> put finger to keyboard and composed:

In article <PT1Sa.94662$N7.11173@sccrnsc03>, Watchit@Comcast.net
mentioned...

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bf9642$l2a$1@bob.news.rcn.net...
[snip]

In any case, this relation has been called Ohm's law for so long, that
regardless of its origin, it *is* Ohm's law. To try and change the
common usage at this late date would just needlessly confuse the issue.

This is sort of like the SI prefix Giga. The standards publications
of NBS (now the NIST), U.S. Navy, ASME (American Society of Mechanical
Eng'rs), and others all show the pronunciation as Jiga, but people
have been mispronouncing it for so long that all hope is lost of ever
going back to the original.

I would think the most sensible pronunciation would be "giga" as this
prefix is derived from the Greek word, "gigas", meaning "giant".

The most mispronounced metric measure, IMO, is kilometre. The correct
pronunciation is kill-oh-meeter, not ki-lometter, if you know what I
mean.

And then there's the mess NIST and the international standards bodies
got us into regarding the binary prefixes (see the last two lines of
my .sig below for the URL). I've yet to hear anyone use those in a
conversation, or even in print. Just remember that 1024 kilobytes is
_not_ called a megabyte anymore!

- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[Franc Zabkar]

On Sun, 20 Jul 2003 08:50:43 +1000, Franc Zabkar
<fzabkar@optussnet.com.au> put finger to keyboard and composed:

On Sat, 19 Jul 2003 09:12:20 -0700, Watson A.Name - 'Watt Sun'
alondra101@hotmail.com> put finger to keyboard and composed:

In article <PT1Sa.94662$N7.11173@sccrnsc03>, Watchit@Comcast.net
mentioned...

"Chuck Harris" <cfharris@erols.com> wrote in message
news:bf9642$l2a$1@bob.news.rcn.net...
[snip]

In any case, this relation has been called Ohm's law for so long, that
regardless of its origin, it *is* Ohm's law. To try and change the
common usage at this late date would just needlessly confuse the issue.

This is sort of like the SI prefix Giga. The standards publications
of NBS (now the NIST), U.S. Navy, ASME (American Society of Mechanical
Eng'rs), and others all show the pronunciation as Jiga, but people
have been mispronouncing it for so long that all hope is lost of ever
going back to the original.

I would think the most sensible pronunciation would be "giga" as this
prefix is derived from the Greek word, "gigas", meaning "giant".

The most mispronounced metric measure, IMO, is kilometre. The correct
pronunciation is kill-oh-meeter,

Or "ki-low-mee-ter".

... not ki-lometter, if you know what I
mean.

And then there's the mess NIST and the international standards bodies
got us into regarding the binary prefixes (see the last two lines of
my .sig below for the URL). I've yet to hear anyone use those in a
conversation, or even in print. Just remember that 1024 kilobytes is
_not_ called a megabyte anymore!


- Franc Zabkar

- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[buck rojerz]

"Sir Charles W. Shults III" <aichipREM@OVEcfl.THISrr.com> wrote in
news:OFFRa.122068$ic1.2487130@twister.tampabay.rr.com:

How hot? One solution is P=EI, where power in watts is equal to
the product
of voltage and current. So the voltage drop across the resistor
multiplied by the current in amps through the resistor will yield
watts of heat created by the resistor.
Now, if you know the composition of the resistor, you can look up
the
specific heat of the material and calculate how much energy it takes
to change its temperature. You will need to know how many joules of
energy have been applied. Calculate the joules by multiplying the
time that the power was applied in seconds by the power in watts. Now
look at the specific heat table and it will tell you how many joules
per Kelvin it takes to raise the temperature.
If you have any physics experience, it will be very simple.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip

Now your getting logical and there is evidently no room for logic in this
thread.