Richard:

Hmmm....

Impedance... let's give it its' proper due!

It was the self taught "electrician", and ultimately Fellow of the Royal
Society, Oliver Heaviside, FRS
[1850 - 1925] who was born in the London slums to a very poor family and who
had never attended
any school beyond the age of 16 who was the person who coined, defined and
first used the terms
"impedance", "admittance", and "reactance".

Oliver Heaviside also gave us Maxwell's Equations in the form we now know
them. Maxwell
wrote his equations in the form of 22 separate equations using the arcane
method of "quaternions".
Heaviside simplified those 22 equations given by Maxwell down to the four
simple equations with
two auxilliary constituent relations that we now know and love.

James Clerk Maxwell was a Cambridge educated mathematician from an affluent
and educated family.
Oliver Heaviside was a poor kid from the London slums who had to go out to
work at age 16 and
never saw the inside of a college or university!

Heaviside never appeared to receive the citation at the ceremony to which he
was invited when he
was inducted as a Fellow of the Royal Society after he was duly elected to
that lofty title by the
greatest Scientists of the day.

"Impedance"... thank you Oliver!

--
Peter K1PO
Indialantic By-the-Sea, FL


"Richard Harrison" wrote in message
...
Steve Nosko wrote:
"Apparently, because of the way the big bang occurred, when we put a
voltage across a resistor current flows in a manner that we discovered
follows the equation called Ohm`s law."

Big bang? Ohm wasn`t around then. He lived 1787 to 1854. Ohm discovered
that current in an electrical resistance is proportional to voltage.

Resistance is the type of impedance (opposition to electrical current)
in which current is locked in step to the applied voltage.

The item called a resistor is the type of resistance that converts
electrical energy to heat energy.

Not all resistances are resistors. Some resistances don`t convert
electrical energy directly into heat. In these non-dissipative
resistances, current drop is in-phase with the applied volts, or voltage
dropped across the resistance is in-phase with current through the
resistance, but it does not cause energy loss. An example of lossless
resistance is the Zo or surge impedance of a transmission line. Zo is
caused by the distributed inductance and capacitance of the line, but
current in the line is in-phase with the voltage across the line. Zo is
the voltage to current ratio of the waves traveling in either direction
on the transmission line. Zo = volts/amps, yet converts no energy to
heat in the lossless line. Another example of lossless resistance is
"radiation resistance". This is the desired antenna load, so it is
hardly a loss. Loss in the wire, earth, and insulators of the antenna
are resistive loads which produce heat but don`t help the signal.

An ohm is the unit of resistance. It is defined at 0-degrees C, of a
uniform column of mercury 106.300 cm long and weighing 14.451 grams. One
ohm is the resistance which drops one voltt when a current of one amp is
passed through it.

Reactances are also defined by their volts to amps ratios (ohms). The
big difference is that reactance does no work and produces no heat.
Opposition to electrical current comes from delay required to store ard
retrieve energy to and from fields in and around the reactances. Current
lags the applied voltage in an inductance. At time = 0, no current flows
into an inductance, but rises exponentially from the instant of initial
energization. Current leads the applied voltage into a capacitance. At
time = 0, full current flows into a capacitance but voltage across the
capacitance is zero and rises exponentially from the instant of initial
energization.

In an a-c circuit, the current through an inductance lags the voltage by
90-degrees. In a a-c circuit, the current through a capacitance leads
the voltage by 90-degrees. Phase shifts are produced by energy storage
in reactance. There is no phase shift in a resistance. No electrical
energy is stored in a resistor, but its matter does have a thermal
capacity. Once its atoms are agitated by heat their inertia is evident
in the resistance`s temperature. It takes time to cool.

Steve wrote: "Things get all messed up."

As old Carson Robinson sang: "Life gets tedious, Don`t it?" Steve gave
the formulas for capacitive and inductive reactances. They have always
seemed convenient to me. Steve says: "---we call this new kind of
(corrupted) resistance "Impedance"."

No. Impedance is the general name for opposition to electricity.
Resistance is the specialized name for the case in which the impedance
alone causes no delay and stores no electrical energy. All electrical
impedance is defined by its voltage to current ratio, and is the total
opposition (resistance and reactance) a circuit offers to the flow of
electricity. For d-c, reactance doesn`t count. For a-c, total opposition
consists of the vector (phasor) sum of resistance and reactance in a
circuit. Impedance is measured in ohms and its reciprocal is called
admittance. The symbol for impedance is Z. The symbol for admittance is
Y.

Steve also writes:
"Poof! BUT converts it into radio frequency energy (RF) also called an
electromagnetic field or wave."

Yes. A radio wave is r-f energy which has escaped the confines of wires
and doesn`t come back. Whenever wires in open space carry high-frequency
current, some energy gets away as a radiated field, having a strength
that varies inversely with the distance.

Best regards, Richard Harrison, KB5WZI

I have been convinced that "impedance" is the ratio of force to response
in any media. That has worked well for me. Maybe there are readers who can
set me straight if I've been wrong.

Jerry



"Peter O. Brackett" wrote in message
news
Richard:

Hmmm....

Impedance... let's give it its' proper due!

It was the self taught "electrician", and ultimately Fellow of the Royal
Society, Oliver Heaviside, FRS
[1850 - 1925] who was born in the London slums to a very poor family and
who
had never attended
any school beyond the age of 16 who was the person who coined, defined and
first used the terms
"impedance", "admittance", and "reactance".

Oliver Heaviside also gave us Maxwell's Equations in the form we now know
them. Maxwell
wrote his equations in the form of 22 separate equations using the arcane
method of "quaternions".
Heaviside simplified those 22 equations given by Maxwell down to the four
simple equations with
two auxilliary constituent relations that we now know and love.

James Clerk Maxwell was a Cambridge educated mathematician from an
affluent
and educated family.
Oliver Heaviside was a poor kid from the London slums who had to go out to
work at age 16 and
never saw the inside of a college or university!

Heaviside never appeared to receive the citation at the ceremony to which
he
was invited when he
was inducted as a Fellow of the Royal Society after he was duly elected to
that lofty title by the
greatest Scientists of the day.

"Impedance"... thank you Oliver!

--
Peter K1PO
Indialantic By-the-Sea, FL


"Richard Harrison" wrote in message
...
Steve Nosko wrote:
"Apparently, because of the way the big bang occurred, when we put a
voltage across a resistor current flows in a manner that we discovered
follows the equation called Ohm`s law."

Big bang? Ohm wasn`t around then. He lived 1787 to 1854. Ohm discovered
that current in an electrical resistance is proportional to voltage.

Resistance is the type of impedance (opposition to electrical current)
in which current is locked in step to the applied voltage.

The item called a resistor is the type of resistance that converts
electrical energy to heat energy.

Not all resistances are resistors. Some resistances don`t convert
electrical energy directly into heat. In these non-dissipative
resistances, current drop is in-phase with the applied volts, or voltage
dropped across the resistance is in-phase with current through the
resistance, but it does not cause energy loss. An example of lossless
resistance is the Zo or surge impedance of a transmission line. Zo is
caused by the distributed inductance and capacitance of the line, but
current in the line is in-phase with the voltage across the line. Zo is
the voltage to current ratio of the waves traveling in either direction
on the transmission line. Zo = volts/amps, yet converts no energy to
heat in the lossless line. Another example of lossless resistance is
"radiation resistance". This is the desired antenna load, so it is
hardly a loss. Loss in the wire, earth, and insulators of the antenna
are resistive loads which produce heat but don`t help the signal.

An ohm is the unit of resistance. It is defined at 0-degrees C, of a
uniform column of mercury 106.300 cm long and weighing 14.451 grams. One
ohm is the resistance which drops one voltt when a current of one amp is
passed through it.

Reactances are also defined by their volts to amps ratios (ohms). The
big difference is that reactance does no work and produces no heat.
Opposition to electrical current comes from delay required to store ard
retrieve energy to and from fields in and around the reactances. Current
lags the applied voltage in an inductance. At time = 0, no current flows
into an inductance, but rises exponentially from the instant of initial
energization. Current leads the applied voltage into a capacitance. At
time = 0, full current flows into a capacitance but voltage across the
capacitance is zero and rises exponentially from the instant of initial
energization.

In an a-c circuit, the current through an inductance lags the voltage by
90-degrees. In a a-c circuit, the current through a capacitance leads
the voltage by 90-degrees. Phase shifts are produced by energy storage
in reactance. There is no phase shift in a resistance. No electrical
energy is stored in a resistor, but its matter does have a thermal
capacity. Once its atoms are agitated by heat their inertia is evident
in the resistance`s temperature. It takes time to cool.

Steve wrote: "Things get all messed up."

As old Carson Robinson sang: "Life gets tedious, Don`t it?" Steve gave
the formulas for capacitive and inductive reactances. They have always
seemed convenient to me. Steve says: "---we call this new kind of
(corrupted) resistance "Impedance"."

No. Impedance is the general name for opposition to electricity.
Resistance is the specialized name for the case in which the impedance
alone causes no delay and stores no electrical energy. All electrical
impedance is defined by its voltage to current ratio, and is the total
opposition (resistance and reactance) a circuit offers to the flow of
electricity. For d-c, reactance doesn`t count. For a-c, total opposition
consists of the vector (phasor) sum of resistance and reactance in a
circuit. Impedance is measured in ohms and its reciprocal is called
admittance. The symbol for impedance is Z. The symbol for admittance is
Y.

Steve also writes:
"Poof! BUT converts it into radio frequency energy (RF) also called an
electromagnetic field or wave."

Yes. A radio wave is r-f energy which has escaped the confines of wires
and doesn`t come back. Whenever wires in open space carry high-frequency
current, some energy gets away as a radiated field, having a strength
that varies inversely with the distance.

Best regards, Richard Harrison, KB5WZI

Jerry Martes wrote:
"I have never been convinced that "impedance" is the ratio of force to
response in any media."

Jerry framed the question very nicely.

The logic seems simple. More force is required when resistance to change
is higher. When current is very small despite high force, it must be due
to high resistance.

Resistance proportional to force (volts) and inversely proportional to
current (amps) seems perfectly logical to me. R=E/I

Best regards, Richard Harrison, KB5WZI

Peter, K1PO wrote:
"Oliver heaviside was a poor kid from the London slums who had to go out
to work at age 16 and never saw the inside of a college or university."

I am aware of Heaviside`s story. He was the idol of one of my professors
who frerquently regaled us with heaviside stories, so he became one of
my favorites too.

Maxwell is not diminished by his advantages. He had the mathematical
background he needed to formulate his equations and the moxie to
speculate that displacement current generates a magnetic field same as a
conduction current does. This is the secret of radiation. Heaviside was
able to improve on the calculus, and simplify and reorganize Maxwell`s
work. Michael Faraday discovered electromagnetic induction and deserves
a lot of credit too. Everybody benefits from the work of others in
complicated fields. Faraday lived 1791-1867. Maxwell lived 1831-1879.
Heaviside lived 1850-1925. This really was during a golden age for the
British.

I had the Maxwell`s equations course many decades ago. Strangely enough,
it was titled "Ultra High Frequency Techniques". You really had to read
the syllabus to know what the course was about.

Best regards, Richard Harrison, KB5WZI

I just love it when those born in the slums of London even tho they went to
work when they were 16 they had enough smarts
to go head to head with the experts. It must be a result of the morning fog
from the river where one learns quickly what is real
and what is not. Going to work for a living
at 16 is not all that bad since it allows you to make personal decisions
that can benefit
before the onset of age makes it too late.
An East Ender
Art



"Peter O. Brackett" wrote in message
news
Richard:

Hmmm....

Impedance... let's give it its' proper due!

It was the self taught "electrician", and ultimately Fellow of the Royal
Society, Oliver Heaviside, FRS
[1850 - 1925] who was born in the London slums to a very poor family and
who
had never attended
any school beyond the age of 16 who was the person who coined, defined and
first used the terms
"impedance", "admittance", and "reactance".

Oliver Heaviside also gave us Maxwell's Equations in the form we now know
them. Maxwell
wrote his equations in the form of 22 separate equations using the arcane
method of "quaternions".
Heaviside simplified those 22 equations given by Maxwell down to the four
simple equations with
two auxilliary constituent relations that we now know and love.

James Clerk Maxwell was a Cambridge educated mathematician from an
affluent
and educated family.
Oliver Heaviside was a poor kid from the London slums who had to go out to
work at age 16 and
never saw the inside of a college or university!

Heaviside never appeared to receive the citation at the ceremony to which
he
was invited when he
was inducted as a Fellow of the Royal Society after he was duly elected to
that lofty title by the
greatest Scientists of the day.

"Impedance"... thank you Oliver!

--
Peter K1PO
Indialantic By-the-Sea, FL


"Richard Harrison" wrote in message
...
Steve Nosko wrote:
"Apparently, because of the way the big bang occurred, when we put a
voltage across a resistor current flows in a manner that we discovered
follows the equation called Ohm`s law."

Big bang? Ohm wasn`t around then. He lived 1787 to 1854. Ohm discovered
that current in an electrical resistance is proportional to voltage.

Resistance is the type of impedance (opposition to electrical current)
in which current is locked in step to the applied voltage.

The item called a resistor is the type of resistance that converts
electrical energy to heat energy.

Not all resistances are resistors. Some resistances don`t convert
electrical energy directly into heat. In these non-dissipative
resistances, current drop is in-phase with the applied volts, or voltage
dropped across the resistance is in-phase with current through the
resistance, but it does not cause energy loss. An example of lossless
resistance is the Zo or surge impedance of a transmission line. Zo is
caused by the distributed inductance and capacitance of the line, but
current in the line is in-phase with the voltage across the line. Zo is
the voltage to current ratio of the waves traveling in either direction
on the transmission line. Zo = volts/amps, yet converts no energy to
heat in the lossless line. Another example of lossless resistance is
"radiation resistance". This is the desired antenna load, so it is
hardly a loss. Loss in the wire, earth, and insulators of the antenna
are resistive loads which produce heat but don`t help the signal.

An ohm is the unit of resistance. It is defined at 0-degrees C, of a
uniform column of mercury 106.300 cm long and weighing 14.451 grams. One
ohm is the resistance which drops one voltt when a current of one amp is
passed through it.

Reactances are also defined by their volts to amps ratios (ohms). The
big difference is that reactance does no work and produces no heat.
Opposition to electrical current comes from delay required to store ard
retrieve energy to and from fields in and around the reactances. Current
lags the applied voltage in an inductance. At time = 0, no current flows
into an inductance, but rises exponentially from the instant of initial
energization. Current leads the applied voltage into a capacitance. At
time = 0, full current flows into a capacitance but voltage across the
capacitance is zero and rises exponentially from the instant of initial
energization.

In an a-c circuit, the current through an inductance lags the voltage by
90-degrees. In a a-c circuit, the current through a capacitance leads
the voltage by 90-degrees. Phase shifts are produced by energy storage
in reactance. There is no phase shift in a resistance. No electrical
energy is stored in a resistor, but its matter does have a thermal
capacity. Once its atoms are agitated by heat their inertia is evident
in the resistance`s temperature. It takes time to cool.

Steve wrote: "Things get all messed up."

As old Carson Robinson sang: "Life gets tedious, Don`t it?" Steve gave
the formulas for capacitive and inductive reactances. They have always
seemed convenient to me. Steve says: "---we call this new kind of
(corrupted) resistance "Impedance"."

No. Impedance is the general name for opposition to electricity.
Resistance is the specialized name for the case in which the impedance
alone causes no delay and stores no electrical energy. All electrical
impedance is defined by its voltage to current ratio, and is the total
opposition (resistance and reactance) a circuit offers to the flow of
electricity. For d-c, reactance doesn`t count. For a-c, total opposition
consists of the vector (phasor) sum of resistance and reactance in a
circuit. Impedance is measured in ohms and its reciprocal is called
admittance. The symbol for impedance is Z. The symbol for admittance is
Y.

Steve also writes:
"Poof! BUT converts it into radio frequency energy (RF) also called an
electromagnetic field or wave."

Yes. A radio wave is r-f energy which has escaped the confines of wires
and doesn`t come back. Whenever wires in open space carry high-frequency
current, some energy gets away as a radiated field, having a strength
that varies inversely with the distance.

Best regards, Richard Harrison, KB5WZI

Howdy,

I have always heard that what we call "Ohm's Law" is actually Cavendish's Law.

But as the story goes, Cavendish didn't write a paper.

Is this BS or true?

Jack, K9CUN

Probably true!

After all Murphy's Law was first postulated by Smith!!

DD

JDer8745 wrote:

Howdy,

I have always heard that what we call "Ohm's Law" is actually Cavendish's Law.

But as the story goes, Cavendish didn't write a paper.

Is this BS or true?

Jack, K9CUN

Hi Richard, TOP and internal posting...sorry folks.

I think you are learned on this subject and won't quibble about what
really happens in the real world. I think you know and I claim that I know.
I will, however pick a little bone in regards to the answer which I
posted to an email since I also thought would help others at a similar level
of understanding or confusion.

Oh geeze! here he goes...you had to set him off..
Here's my mantra and why a I am a little miffed by (but actually understand)
frequent attempts to correct my explanations.
The words we use and the depth to which we go at any given point to
describe things, have an effect on the ability of people to absorb the
concepts. As an instructor of basics, I have worked very hard, for a long
time, to understand and use effective ways to transfer an understanding of
electronic principles to students at what might be considered the lower
rungs of the technical ladder...the beginners...the hams also. There is
what I'll call an "instructor's high" associated with the light bulb going
on in a student. It's really cool.
I carefully craft my responses to the apparent level of knowledge of the
questioner. I do my best to form a coherent story which progresses from
simple, where a concept needed to understand more complex concepts is
explained first, without adding the unnecessary complications of true, but
potentially confusing facts, to the more complex goal I perceive to be the
questioner's goal. Once the basic concepts sinks in AND the student is
ready for the next level, usually by a response, I then proceed to build. It
is the old "speak to your audience" concept.
I don't dispute that your explanations are correct. They appear very
good, rather complete. I do believe however, that your most assuredly
honest and well meaning attempt to be correct, completely correct, actually
makes the subject more confusing to the beginner. I believe this because I
have been there. In fact, I must, almost every class session, throttle
myself from doing just the very same thing. Why? Because when I do, I have
succeeded in causing more confusion, resulting in a mental block to learning
which requires much more effort at damage control to erase the mental
blockage I created with my ignorant desire to be completely correct. Please
understand that I am being harsh on *myself* because I have been frustrated
by this and work hard to keep it under control. As an Engineer, teaching
technician students, one must keep in mind that there is a different state
of mind and ability to absorb what to them, appears a very complex
subject...but to my arrogant mind is really very simple. After all,
piecewise parametric polynomial interpolation looked like an impossible
concept, way beyond my comprehension back in 92 when I first saw reference
to it. Now, it looks like the simplest thing any high school Algebra
student can understand.

I'm also at a point in my life that I have seen and done so much in
this field (and it all seems so simple) that I wish to return some of it to
others, and I wish to do it very effectively.

Of course, now you're going to tell me that you also have been teaching for
x years and your methods are equally successful...so be it. There needs to
me more of us.

BTW...what is your line, Richard?

Some comments, corrections and whatever stuck my fancy about what you
wrote...


"Richard Harrison" wrote in message
...
Steve Nosko wrote:
"Apparently, because of the way the big bang occurred, when we put a
voltage across a resistor current flows in a manner that we discovered
follows the equation called Ohm`s law."

Big bang? Ohm wasn`t around then. He lived 1787 to 1854. Ohm discovered
that current in an electrical resistance is proportional to voltage.

The concept I was trying to relate in a slightly 'light' manner was:
The stuff that happens, happens 'cuz of what we call "physics",
"physical laws" or "nature" or sump-in' like that, not because there is an
equation making it happen. Resistors don't know Ohm's law and don't conduct
current because of Ohm or his discoveries.

The equation we call Ohm's law is simply a model of how reality works.
Like a model airplane, which helps us understand what a real airplane looks
like. Ohms law, and all the other equations, help us understand what real
electronics "looks like".


Resistance is the type of impedance (opposition to electrical current)
in which current is locked in step to the applied voltage.

A completely valid way to word it, but to a beginner I think the phrase
"locked in step " is vague. It would be a good start, but probably needs
expansion to explain what it means.



The item called a resistor is the type of resistance that converts
electrical energy to heat energy.
Not all resistances are resistors.

I wouldn't have worded it that way, but it (resistor is the type of
resistance) is a valid model to have in mind. That is, as a way to
distinguish it from "a resistance which is not a resistor". This made me
think of how I think of it.. and when I use the word "resistance" I think of
it as as a resistor, yet an impedance has a real or "resistive" part. That
word "resistance" for me conotes a "resistor" where the others conote the
other concept. Interesting nomenclature, that's all.

Some resistances don`t convert
electrical energy directly into heat. In these non-dissipative
resistances,

Well, here's where I'll say that I think this is truly a matter of
symantics. Your terminlolgy implies that dissipation = heat. I agree that
the most common usage it that "... is dissipated as heat...". However, this
next bit:
...is in-phase with current through the
resistance, but it does not cause energy loss.

I think has a symantics problem. I'm sure you truly understand what
happens, but the words "...does not cause energy loss." isn't correct,
because the energy IS lost from the circuit. The circuit "can't tell" the
difference 'tween the resistor and any other kind of resistive component.
It just may or may not be as heat, right?
You know what happens and I know what happens, but the OP didn't, so
I was starting him down a path that wouldn't paint him into a corner of not
being able to understand the other resistive types of things later...if so
desired.


An example of lossless
resistance is the Zo or surge impedance of a transmission line.

Again, the power IS lost from the source, no? I think this an important
basic understanding. To the sourse, it is gone. Poof! never to be seen
again. I think it is a good model to understand and helps go further
without Maxwell complicating things. I think you can go pretty far without
Maxwell (gee, twice in one paragraph) and still have a good amount of
(correct) sixth sense about what is going on in electronics and transmission
lines.


Zo is ... yet converts no energy to heat in the lossless line.

And my model didn't exclude this. I thought I was explicit about
that without bringing in more complexity for the OP.


"radiation resistance". ...is hardly a loss.

Again, as far as the transmitter circuitry is concerned, it is.


The following is a well done explanation which goes further and into
more detail...with one disagreement.

An ohm is the unit of resistance. It is defined at 0-degrees C, of a
uniform column of mercury 106.300 cm long and weighing 14.451 grams. One
ohm is the resistance which drops one voltt when a current of one amp is
passed through it.

Reactances are also defined by their volts to amps ratios (ohms). The
big difference is that reactance does no work and produces no heat.
Opposition to electrical current comes from delay required to store ard
retrieve energy to and from fields in and around the reactances. Current
lags the applied voltage in an inductance. At time = 0, no current flows
into an inductance, but rises exponentially from the instant of initial
energization. Current leads the applied voltage into a capacitance. At
time = 0, full current flows into a capacitance but voltage across the
capacitance is zero and rises exponentially from the instant of initial
energization.

In an a-c circuit, the current through an inductance lags the voltage by
90-degrees. In a a-c circuit, the current through a capacitance leads
the voltage by 90-degrees. Phase shifts are produced by energy storage
in reactance. There is no phase shift in a resistance. No electrical
energy is stored in a resistor, but its matter does have a thermal
capacity. Once its atoms are agitated by heat their inertia is evident
in the resistance`s temperature. It takes time to cool.

Steve wrote: "Things get all messed up."

As old Carson Robinson sang: "Life gets tedious, Don`t it?" Steve gave
the formulas for capacitive and inductive reactances. They have always
seemed convenient to me. Steve says: "---we call this new kind of
(corrupted) resistance "Impedance"."

No. Impedance is the general name for opposition to electricity.

No. In the context of my writing for someone who has an unserstanding
of DC and resistance, reactance it a very confusing factor. It corrupts an
otherwise simple world. Getting into Vector Algebra and phasors is a
significant step up in mathematics for the beginner not inclined to go the
Engineering route. What I'm saying is that although the unified field
theory may very well be the absolutely correct explanation of everything in
the universe, we don't need to explain it fully in the beginning to help
someone understand Gravity's acceleration, F=MA and you can't push a rope.
Newton certainly didn't need it. For all I know, F=MA may very well be a
special case in quantum mechanics, but I don't need it to calculate
accelerations, velocities, etc


Resistance is the specialized name for the case in which the impedance
alone causes no delay and stores no electrical energy. All electrical
impedance is defined by its voltage to current ratio, and is the total
opposition (resistance and reactance) a circuit offers to the flow of
electricity. For d-c, reactance doesn`t count. For a-c, total opposition
consists of the vector (phasor) sum of resistance and reactance in a
circuit. Impedance is measured in ohms and its reciprocal is called
admittance. The symbol for impedance is Z. The symbol for admittance is
Y.

Steve also writes:
"Poof! BUT converts it into radio frequency energy (RF) also called an
electromagnetic field or wave."

Yes. A radio wave is r-f energy which has escaped the confines of wires
and doesn`t come back. Whenever wires in open space carry high-frequency
current, some energy gets away as a radiated field, having a strength
that varies inversely with the distance.

Best regards, Richard Harrison, KB5WZI

Steve, I also tried to give back and taught at a junior college for a couple
of years but I found out that talking and communicating were two different
things. If what you do
succeeds in comunicating then you are doing good where others have failed by
resorting to just talking or handing out books. By you "communicating" you
encourage independent thought which is so much better than relying just on
memory and underlined quotes.
If you are winning then keep at it and disregard comments that are without
depth.
Cheers
Art

"Steve Nosko" wrote in message
...
Hi Richard, TOP and internal posting...sorry folks.

I think you are learned on this subject and won't quibble about what
really happens in the real world. I think you know and I claim that I
know.
I will, however pick a little bone in regards to the answer which I
posted to an email since I also thought would help others at a similar
level
of understanding or confusion.

Oh geeze! here he goes...you had to set him off..
Here's my mantra and why a I am a little miffed by (but actually
understand)
frequent attempts to correct my explanations.
The words we use and the depth to which we go at any given point to
describe things, have an effect on the ability of people to absorb the
concepts. As an instructor of basics, I have worked very hard, for a long
time, to understand and use effective ways to transfer an understanding of
electronic principles to students at what might be considered the lower
rungs of the technical ladder...the beginners...the hams also. There is
what I'll call an "instructor's high" associated with the light bulb going
on in a student. It's really cool.
I carefully craft my responses to the apparent level of knowledge of
the
questioner. I do my best to form a coherent story which progresses from
simple, where a concept needed to understand more complex concepts is
explained first, without adding the unnecessary complications of true, but
potentially confusing facts, to the more complex goal I perceive to be the
questioner's goal. Once the basic concepts sinks in AND the student is
ready for the next level, usually by a response, I then proceed to build.
It
is the old "speak to your audience" concept.
I don't dispute that your explanations are correct. They appear very
good, rather complete. I do believe however, that your most assuredly
honest and well meaning attempt to be correct, completely correct,
actually
makes the subject more confusing to the beginner. I believe this because
I
have been there. In fact, I must, almost every class session, throttle
myself from doing just the very same thing. Why? Because when I do, I
have
succeeded in causing more confusion, resulting in a mental block to
learning
which requires much more effort at damage control to erase the mental
blockage I created with my ignorant desire to be completely correct.
Please
understand that I am being harsh on *myself* because I have been
frustrated
by this and work hard to keep it under control. As an Engineer, teaching
technician students, one must keep in mind that there is a different state
of mind and ability to absorb what to them, appears a very complex
subject...but to my arrogant mind is really very simple. After all,
piecewise parametric polynomial interpolation looked like an impossible
concept, way beyond my comprehension back in 92 when I first saw reference
to it. Now, it looks like the simplest thing any high school Algebra
student can understand.

I'm also at a point in my life that I have seen and done so much
in
this field (and it all seems so simple) that I wish to return some of it
to
others, and I wish to do it very effectively.

Of course, now you're going to tell me that you also have been teaching
for
x years and your methods are equally successful...so be it. There needs
to
me more of us.

BTW...what is your line, Richard?

Some comments, corrections and whatever stuck my fancy about what you
wrote...


"Richard Harrison" wrote in message
...
Steve Nosko wrote:
"Apparently, because of the way the big bang occurred, when we put a
voltage across a resistor current flows in a manner that we discovered
follows the equation called Ohm`s law."

Big bang? Ohm wasn`t around then. He lived 1787 to 1854. Ohm discovered
that current in an electrical resistance is proportional to voltage.

The concept I was trying to relate in a slightly 'light' manner was:
The stuff that happens, happens 'cuz of what we call "physics",
"physical laws" or "nature" or sump-in' like that, not because there is an
equation making it happen. Resistors don't know Ohm's law and don't
conduct
current because of Ohm or his discoveries.

The equation we call Ohm's law is simply a model of how reality works.
Like a model airplane, which helps us understand what a real airplane
looks
like. Ohms law, and all the other equations, help us understand what real
electronics "looks like".


Resistance is the type of impedance (opposition to electrical current)
in which current is locked in step to the applied voltage.

A completely valid way to word it, but to a beginner I think the
phrase
"locked in step " is vague. It would be a good start, but probably needs
expansion to explain what it means.



The item called a resistor is the type of resistance that converts
electrical energy to heat energy.
Not all resistances are resistors.

I wouldn't have worded it that way, but it (resistor is the type
of
resistance) is a valid model to have in mind. That is, as a way to
distinguish it from "a resistance which is not a resistor". This made me
think of how I think of it.. and when I use the word "resistance" I think
of
it as as a resistor, yet an impedance has a real or "resistive" part.
That
word "resistance" for me conotes a "resistor" where the others conote the
other concept. Interesting nomenclature, that's all.

Some resistances don`t convert
electrical energy directly into heat. In these non-dissipative
resistances,

Well, here's where I'll say that I think this is truly a matter of
symantics. Your terminlolgy implies that dissipation = heat. I agree
that
the most common usage it that "... is dissipated as heat...". However,
this
next bit:
...is in-phase with current through the
resistance, but it does not cause energy loss.

I think has a symantics problem. I'm sure you truly understand what
happens, but the words "...does not cause energy loss." isn't correct,
because the energy IS lost from the circuit. The circuit "can't tell" the
difference 'tween the resistor and any other kind of resistive component.
It just may or may not be as heat, right?
You know what happens and I know what happens, but the OP didn't,
so
I was starting him down a path that wouldn't paint him into a corner of
not
being able to understand the other resistive types of things later...if so
desired.


An example of lossless
resistance is the Zo or surge impedance of a transmission line.

Again, the power IS lost from the source, no? I think this an
important
basic understanding. To the sourse, it is gone. Poof! never to be seen
again. I think it is a good model to understand and helps go further
without Maxwell complicating things. I think you can go pretty far
without
Maxwell (gee, twice in one paragraph) and still have a good amount of
(correct) sixth sense about what is going on in electronics and
transmission
lines.


Zo is ... yet converts no energy to heat in the lossless line.

And my model didn't exclude this. I thought I was explicit about
that without bringing in more complexity for the OP.


"radiation resistance". ...is hardly a loss.

Again, as far as the transmitter circuitry is concerned, it is.


The following is a well done explanation which goes further and
into
more detail...with one disagreement.

An ohm is the unit of resistance. It is defined at 0-degrees C, of a
uniform column of mercury 106.300 cm long and weighing 14.451 grams. One
ohm is the resistance which drops one voltt when a current of one amp is
passed through it.

Reactances are also defined by their volts to amps ratios (ohms). The
big difference is that reactance does no work and produces no heat.
Opposition to electrical current comes from delay required to store ard
retrieve energy to and from fields in and around the reactances. Current
lags the applied voltage in an inductance. At time = 0, no current flows
into an inductance, but rises exponentially from the instant of initial
energization. Current leads the applied voltage into a capacitance. At
time = 0, full current flows into a capacitance but voltage across the
capacitance is zero and rises exponentially from the instant of initial
energization.

In an a-c circuit, the current through an inductance lags the voltage by
90-degrees. In a a-c circuit, the current through a capacitance leads
the voltage by 90-degrees. Phase shifts are produced by energy storage
in reactance. There is no phase shift in a resistance. No electrical
energy is stored in a resistor, but its matter does have a thermal
capacity. Once its atoms are agitated by heat their inertia is evident
in the resistance`s temperature. It takes time to cool.

Steve wrote: "Things get all messed up."

As old Carson Robinson sang: "Life gets tedious, Don`t it?" Steve gave
the formulas for capacitive and inductive reactances. They have always
seemed convenient to me. Steve says: "---we call this new kind of
(corrupted) resistance "Impedance"."

No. Impedance is the general name for opposition to electricity.

No. In the context of my writing for someone who has an unserstanding
of DC and resistance, reactance it a very confusing factor. It corrupts
an
otherwise simple world. Getting into Vector Algebra and phasors is a
significant step up in mathematics for the beginner not inclined to go the
Engineering route. What I'm saying is that although the unified field
theory may very well be the absolutely correct explanation of everything
in
the universe, we don't need to explain it fully in the beginning to help
someone understand Gravity's acceleration, F=MA and you can't push a rope.
Newton certainly didn't need it. For all I know, F=MA may very well be a
special case in quantum mechanics, but I don't need it to calculate
accelerations, velocities, etc


Resistance is the specialized name for the case in which the impedance
alone causes no delay and stores no electrical energy. All electrical
impedance is defined by its voltage to current ratio, and is the total
opposition (resistance and reactance) a circuit offers to the flow of
electricity. For d-c, reactance doesn`t count. For a-c, total opposition
consists of the vector (phasor) sum of resistance and reactance in a
circuit. Impedance is measured in ohms and its reciprocal is called
admittance. The symbol for impedance is Z. The symbol for admittance is
Y.

Steve also writes:
"Poof! BUT converts it into radio frequency energy (RF) also called an
electromagnetic field or wave."

Yes. A radio wave is r-f energy which has escaped the confines of wires
and doesn`t come back. Whenever wires in open space carry high-frequency
current, some energy gets away as a radiated field, having a strength
that varies inversely with the distance.

Best regards, Richard Harrison, KB5WZI

teve Nosko wrote:
"BTW--what is your line, Richard?"

I apologize for a critical tone in my response to Steve`s posting. An
ancient previous discussion of dissipationless resistance in this
newsgroup leaves me primed to comment when it appears unappreciated.

Dissipationless resistance is the stuff which allows a Class C amplifier
exceed 50% efficiency.

I won`t say I`ve been teaching X years, as I`ve never had that role.
Long ago, I found my patience and temperament unsuited to tutoring. I am
a long retired electrical engineer and find entertainment in the
newsgroups.

Best regards, Richard Harrison, KB5WZI