Displacement current
 

On Nov 21, 1:28*pm, "Dave" wrote:
"Richard Harrison" wrote in message

...

Art wrote:
"The Physics World states that displacement current does not exist with
respect to radiation---."

Who and where?

Be reasonable. Free space is normally nonconductive.

remember, art believes space is full of magic jumping diamagnetic levitating
neutrinos, obviously they carry the charge so there is no need for
displacement current, only the weak force.

Not so. I am willing to believe what modern science say that the
aether is filled with
a circulating magnetic field thru which particles can pass. If that is
what they think that is fine by me.
After all there must be something inside the arbritary border of the
Aether to prevent it collapsing per Newton
Art

Displacement current
 

christofire wrote:

I hardly dare to say it but, actually that's incorrect for the radiation
field (which is what I wrote about). The radiation resistance of an antenna
accounts for its ability to radiate power into the surrounding space and,
like all other resistances, the peak of current co-insides with the peak of
applied voltage - so one doesn't occur '1/2-period later' at all. What's
described in the passage above is the situation in respect of the temporary
storage of energy in the 'reactive near fields' corresponding to a reactive
component of the terminal impedance, not the radiation resistance. I would
expect the latter to be of greater importance to those interested in
communication.

I wouldn't disagree with the statement that stored energy is concentrated in
the regions near the 'maximum charge regions' but if you plot the equipotent
lines around a dipole and equate the amount of energy stored to the electric
field strength it illustrates that the spatial distribution of energy in the
electric field is similar to that in the magnetic field ... as one might
expect.

Chris

That's a good explanation. It might help some people to visualize the
process by comparing it to a series RLC circuit, which its feedpoint
impedance resembles over a moderate bandwidth. In both an RLC circuit
and an antenna, the current and voltage aren't in phase, but they're not
exactly in quadrature (90 degrees out of phase) either. This means that
during each cycle, some of the energy entering the RLC circuit or
antenna is stored and some is consumed. In the RLC circuit, the stored
energy is stored in fields in the capacitor and inductor; in the
antenna, it's stored in fields near the antenna -- the near field. And
the consumed power is dissipated in the resistor in the RLC circuit; in
the antenna, it's radiated. The antenna's equivalent to the RLC circuit
resistance is, of course, the radiation resistance, which "consumes" --
radiates -- some of the applied energy each cycle.

Roy Lewallen, W7EL

Displacement current
 

Richard Harrison wrote:
Michael Faraday (1791- 1867) wrote:
E = F/Q where E & F are parallel vectors. E = the electric field
strength in force per unit charge and F is measured in newtons per
coulomb.

Faraday should have written that E is in units of newtons per coulomb,
as F would obviously be in newtons.

Electrostatic does not mean stationary.

In what way does it not?

73, ac6xg

Displacement current
 

Chris wrote:
"I hardly dare say it but, actually that`s incorrect for the radiation
field (which is what I wrote about)."

That`s chris` prerogative. Note the near field is also called the
"induction field". One reason, its energy returns to the source each
cycle. The far field emergy has escaped or radiated. Its energy appears
as a resistive load on the source.

Best regards, Richard Harrison, KB5WZI

Displacement current
 

Richard Harrison wrote:

...
I now think "evoke" should have been used in place of "invoke".

Best regards, Richard Harrison, KB5WZI


Richard:

I am sure there is, most-probably, enough difference for argument ...

However, to a poor country boy like myself, these terms are, for the
most part, interchangeable ... both can be found with definitions which
bring "magic", "mystery" and the "spiritual realm" into mind ... and, I
am sorry, sometimes I "just feel" this way (and, especially when it is
the "wifes time of the month!") ... grin

Sorry, just thought a bit of sick humor might be appreciated by some ...
LOL! and-a-evil-grin

Regards,
JS

Displacement current
 

Richard Harrison wrote:
Chris wrote:
"I hardly dare say it but, actually that`s incorrect for the radiation
field (which is what I wrote about)."

That`s chris` prerogative. Note the near field is also called the
"induction field". One reason, its energy returns to the source each
cycle. The far field emergy has escaped or radiated. Its energy appears
as a resistive load on the source.

Best regards, Richard Harrison, KB5WZI


You mean, those "antenna/rf-magnetic-fields" are NOT leaving the
radiator at the speed of light, but being "stored in the ether?", to
then collapse and induce an electric field back into the element which
first generated-such? sly-grin

Sorry, I know, this will be perceived as "troll-territory." :-(

Regards,
JS

Displacement current
 

On Nov 21, 4:03*pm, John Smith wrote:
Richard Harrison wrote:
...
I now think "evoke" should have been used in place of "invoke".

Best regards, Richard Harrison, KB5WZI

Richard:

I am sure there is, most-probably, enough difference for argument ...

However, to a poor country boy like myself, these terms are, for the
most part, interchangeable ... both can be found with definitions which
bring "magic", "mystery" and the "spiritual realm" into mind ... and, I
am sorry, sometimes I "just feel" this way (and, especially when it is
the "wifes time of the month!") ... grin

Sorry, just thought a bit of sick humor might be appreciated by some ...
LOL! *and-a-evil-grin

Regards,
JS

No JS THEY ARE NOT INTERCHANGEABLE
You can't insert units that state it is a current and
in the same breath say it does not produce a magnetic field
Best regards
Art

Displacement current
 

Art Unwin wrote:

...
No JS THEY ARE NOT INTERCHANGEABLE
You can't insert units that state it is a current and
in the same breath say it does not produce a magnetic field
Best regards
Art

Interesting ...

EVOKE:
# arouse: call forth (emotions, feelings, and responses); "arouse pity";
"raise a smile"; "evoke sympathy"
# provoke: evoke or provoke to appear or occur; "Her behavior provoked a
quarrel between the couple"
# educe: deduce (a principle) or construe (a meaning); "We drew out some
interesting linguistic data from the native informant"
# raise: summon into action or bring into existence, often as if by
magic; "raise the specter of unemployment"; "he conjured wild birds in
the air"; "call down the spirits from the mountain"
# suggest: call to mind; "this remark evoked sadness"
wordnet.princeton.edu/perl/webwn

INVOKE:
# raise: summon into action or bring into existence, often as if by
magic; "raise the specter of unemployment"; "he conjured wild birds in
the air ...
# cite as an authority; resort to; "He invoked the law that would save
him"; "I appealed to the law of 1900"; "She invoked an ancient law"
# appeal: request earnestly (something from somebody); ask for aid or
protection; "appeal to somebody for help"; "Invoke God in times of trouble"
wordnet.princeton.edu/perl/webwn

Gee, I am "feeling for you", just can't "reach you", but then, you
already knew that ... :-(

Regards,
JS

Displacement current
 

Jim Kelley wrote:
"In what way is it (an electrostatic field) not (stationary)?"

Terman was refering to an electromagnetic (radio) wave. It is a
peculiarity of "old-speak" to call an electric field an electrostatic
field.

As Cecil reminds us, radio waves are always in motion. But, their
superposition may produce a stationary wave called a standing wave.

Best regards, Richard Harrison, KB5WZI

Displacement current
 

On Nov 21, 5:47*pm, (Richard Harrison)
wrote:
Jim Kelley wrote:

"In what way is it (an electrostatic field) not (stationary)?"

Terman was refering to an electromagnetic (radio) wave. It is a
peculiarity of "old-speak" to call an electric field an electrostatic
field.

As Cecil reminds us, radio waves are always in motion. But, their
superposition may produce a stationary wave called a standing wave.

Best regards, Richard Harrison, KB5WZI

But Cecil has never said you can have current flow without a magnetic
field!
So now one must determine where the reflection occurs and science
puports that it is not at the end of the antenna!
Thus the term "standing wave" must be thougherly defined in line with
the newly disclosed facts so that all jive.
Also, Gauss never assumed the wave description over a particle
description, The answer regarding waves and particles
with respect to radiation has not yet been resolved by the scientific
community because of the Maxwell additive dillema.
And "Old speak" doesn't cut the mustard in present day debate. It is
completely wrong to call a static field an electrical field.
It is either a static or a dynamic field so guessing what Terman
really ment or meant to say just does not have any standing.