mutual capacitance?

[RichD]

Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich

 

[Jasen Betts]

On 2019-02-11, RichD <r_delaney2001@yahoo.com> wrote:

Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

you'll see something like mutual capacitance in piezo-electric transformers.



--
When I tried casting out nines I made a hash of it.

 

[Phil Hobbs]

On 2/11/19 5:58 PM, RichD wrote:

Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich

There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Tue, 12 Feb 2019 10:33:31 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2/11/19 5:58 PM, RichD wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich


There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Cheers

Phil Hobbs

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.

Where is the universe's ground lug?


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Phil Hobbs]

On 2/12/19 11:47 AM, John Larkin wrote:

On Tue, 12 Feb 2019 10:33:31 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2/11/19 5:58 PM, RichD wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich


There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Cheers

Phil Hobbs

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.

Where is the universe's ground lug?

Well, there's some silly speculation about that we're living in a
simulation, in which case it would be Node 0.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Tue, 12 Feb 2019 11:58:57 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2/12/19 11:47 AM, John Larkin wrote:
On Tue, 12 Feb 2019 10:33:31 -0500, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2/11/19 5:58 PM, RichD wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich


There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Cheers

Phil Hobbs

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.

Where is the universe's ground lug?



Well, there's some silly speculation about that we're living in a
simulation, in which case it would be Node 0.

Cheers

Phil Hobbs

We could connect to the celestial sphere, the one with all the track
lights.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[RichD]

On February 12, John Larkin wrote:

Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.

2-wire, 3-wire?
Explicate please -

--
Rich

 

[RichD]

On February 12, Phil Hobbs wrote:

Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

I picture the analog of two isolated coils, magnetically
linked: two isolated capacitors, the flux of the 'primary'
transmits through the 'secondary'. Why no such device?

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Well, I have in mind your basic two plate capacitor.
I don't recall self-capacitance -

--
Rich

 

[Phil Hobbs]

On 2/12/19 6:17 PM, RichD wrote:

On February 12, Phil Hobbs wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

I picture the analog of two isolated coils, magnetically
linked: two isolated capacitors, the flux of the 'primary'
transmits through the 'secondary'. Why no such device?


A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Well, I have in mind your basic two plate capacitor.
I don't recall self-capacitance -

--
Rich

What you're describing is precisely the mutual capacitance. It's the
change of the charge on plate 1 due to the change in voltage on plate 2.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[whit3rd]

On Tuesday, February 12, 2019 at 3:17:53 PM UTC-8, RichD wrote:

On February 12, Phil Hobbs wrote:

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Well, I have in mind your basic two plate capacitor.
I don't recall self-capacitance -

Self-capacitance is the capacitance of an object with respect to ground, when it is
in a large grounded box. An infinite box, ideally.

 

[Phil Hobbs]

On 2/12/19 8:14 PM, whit3rd wrote:

On Tuesday, February 12, 2019 at 3:17:53 PM UTC-8, RichD wrote:
On February 12, Phil Hobbs wrote:

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Well, I have in mind your basic two plate capacitor.
I don't recall self-capacitance -

Self-capacitance is the capacitance of an object with respect to ground, when it is
in a large grounded box. An infinite box, ideally.

Ground isn't necessary. An isolated conductor with a certain amount Q
of free charge on it will have an E field. The voltage V is minus the
line integral of E dot ds from the surface to infinity. The
self-capacitance is Q/V.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[George Herold]

On Tuesday, February 12, 2019 at 10:33:40 AM UTC-5, Phil Hobbs wrote:

On 2/11/19 5:58 PM, RichD wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich


There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.

Huh right, I had this picture of three hunks of stuff with various
inter-capacitances. But that starts with one hunk!

George H.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Tue, 12 Feb 2019 15:12:11 -0800 (PST), RichD
<r_delaney2001@yahoo.com> wrote:

On February 12, John Larkin wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.


2-wire, 3-wire?
Explicate please -

https://www.dropbox.com/s/ir45h6qd8gjryl0/2wire_3wire.JPG?dl=0

The 3-wire measurement ignores Cy and Cz.

If the moon moved away from earth, Cem would approach zero, but Ceu
and Cmu wouldn't change.

Most good c-meters will do 3-wire measurement, which allows a small
cap to be measured at the ends of coaxial cables.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[John Larkin]

On Tue, 12 Feb 2019 17:55:41 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Tuesday, February 12, 2019 at 10:33:40 AM UTC-5, Phil Hobbs wrote:
On 2/11/19 5:58 PM, RichD wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.


--
Rich


There is. It's usually just called 'capacitance', unless you need to
distinguish it from self-capacitance.

A 1-cm radius isolated sphere has a self-capacitance of 1 cm (Gaussian
units), which is about 1.12 pF.
Huh right, I had this picture of three hunks of stuff with various
inter-capacitances. But that starts with one hunk!

George H.

Just get a ball bearing floating in space and throw electrons at it.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[George Herold]

On Wednesday, February 13, 2019 at 12:56:49 AM UTC-5, John Larkin wrote:

On Tue, 12 Feb 2019 15:12:11 -0800 (PST), RichD
r_delaney2001@yahoo.com> wrote:

On February 12, John Larkin wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.


2-wire, 3-wire?
Explicate please -

https://www.dropbox.com/s/ir45h6qd8gjryl0/2wire_3wire.JPG?dl=0

The 3-wire measurement ignores Cy and Cz.

If the moon moved away from earth, Cem would approach zero, but Ceu
and Cmu wouldn't change.

Most good c-meters will do 3-wire measurement, which allows a small
cap to be measured at the ends of coaxial cables.

OK we should be able to work out the earth-moon capacitance as a
physics problem.
Here it is using method of images.
http://www.iue.tuwien.ac.at/phd/wasshuber/node77.html

(Hmm that is for sphere's of equal radius.)

As a first approximation we could guess that the Earth's C to the
universe is decreased by the ratio of the field lines that hit the
moon, to all of them... Which is pi*R_moon ^2/ (4*pi*Dist_E-M^2)
R_earth ~6.4 x10^6 m C_earth ~ 640 uF
R_moon ~1.7 x10^6 m
and Dist_E-M ~3.8x10^8 m.

Putting that all in.. and hopefully making no mistakes I get a drcrease
of 5x10^-6 or C_e-m ~3,200 pF .... 3.2 nF
What was your number for C_e-m?

George H.

Of course this is going to only be true at low frequency...
Speed of light and all.

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[George Herold]

On Wednesday, February 13, 2019 at 10:14:31 AM UTC-5, George Herold wrote:

On Wednesday, February 13, 2019 at 12:56:49 AM UTC-5, John Larkin wrote:
On Tue, 12 Feb 2019 15:12:11 -0800 (PST), RichD
r_delaney2001@yahoo.com> wrote:

On February 12, John Larkin wrote:
Looking at network theory and the duality theorems,
why is there no mutual capacitance? i.e. electric
flux linkages, symmetric to mutual inductance and B flux.

There are two commonly given values for the capacitance between the
earth and the moon, 160uF and 3 uF. I think one is 2-wire capacitance
and the smaller one is 3-wire.


2-wire, 3-wire?
Explicate please -

https://www.dropbox.com/s/ir45h6qd8gjryl0/2wire_3wire.JPG?dl=0

The 3-wire measurement ignores Cy and Cz.

If the moon moved away from earth, Cem would approach zero, but Ceu
and Cmu wouldn't change.

Most good c-meters will do 3-wire measurement, which allows a small
cap to be measured at the ends of coaxial cables.

OK we should be able to work out the earth-moon capacitance as a
physics problem.
Here it is using method of images.
http://www.iue.tuwien.ac.at/phd/wasshuber/node77.html

(Hmm that is for sphere's of equal radius.)

As a first approximation we could guess that the Earth's C to the
universe is decreased by the ratio of the field lines that hit the
moon, to all of them... Which is pi*R_moon ^2/ (4*pi*Dist_E-M^2)
R_earth ~6.4 x10^6 m C_earth ~ 640 uF
R_moon ~1.7 x10^6 m
and Dist_E-M ~3.8x10^8 m.

Putting that all in.. and hopefully making no mistakes I get a drcrease
of 5x10^-6 or C_e-m ~3,200 pF .... 3.2 nF
What was your number for C_e-m?

George H.

Hmm there's this,
https://electronics.stackexchange.com/questions/111582/capacitance-between-earth-and-moon

I'm going to say it's wrong.
It does have your 160 uF and 3 uF numbers... but
just engineers plugging in numbers.
(first time I've called B. Pease, just an engineer :^)

GH

Of course this is going to only be true at low frequency...
Speed of light and all.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[jfeng@my-deja.com]

On Wednesday, February 13, 2019 at 7:14:31 AM UTC-8, George Herold wrote:

OK we should be able to work out the earth-moon capacitance as a
physics problem.
This is one of the solved problems in Maxwell's "Treatise on Electricity and Magnetism". Of course, this was before we had mks units, so the answer is given in meters instead of farads (or maybe he was jealous of Michael Faraday).

 

[George Herold]

On Wednesday, February 13, 2019 at 10:51:51 AM UTC-5, jf...@my-deja.com wrote:

On Wednesday, February 13, 2019 at 7:14:31 AM UTC-8, George Herold wrote:
OK we should be able to work out the earth-moon capacitance as a
physics problem.
This is one of the solved problems in Maxwell's "Treatise on Electricity and Magnetism". Of course, this was before we had mks units, so the answer is given in meters instead of farads (or maybe he was jealous of Michael Faraday).

Well what's his answer? The cgs unit of capacitance is the cm. But we
can convert it. (And if we make a mistake we'll beg Phil H. for help.)

https://en.wikipedia.org/wiki/Centimetre%E2%80%93gram%E2%80%93second_system_of_units#Electromagnetic_units_in_various_CGS_systems

George h.

 

[jfeng@my-deja.com]

On Wednesday, February 13, 2019 at 8:13:58 AM UTC-8, George Herold wrote:

Well what's his answer?
I don't remember, and my copy of Maxwell's Treatise is packed away. It should be easy to find a copy, so YCLIU (try Google). I vaguely recall that you needed a scaling factor of (1/4πε0) to convert it to mks.

 

[Phil Hobbs]

On 2/13/19 10:51 AM, jfeng@my-deja.com wrote:

On Wednesday, February 13, 2019 at 7:14:31 AM UTC-8, George Herold wrote:
OK we should be able to work out the earth-moon capacitance as a
physics problem.
This is one of the solved problems in Maxwell's "Treatise on Electricity and Magnetism". Of course, this was before we had mks units, so the answer is given in meters instead of farads (or maybe he was jealous of Michael Faraday).

1 pF = 1.12 cm

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com