Correct me if I'm wrong, but didn't Ben Franklin, when he was doing his
experiments with electricity, put to plates close together hooked up to his
static generator, & charge them? That part I'm pretty sure is true. But it
seems like he then could take one of the plates away for a while & when he
put it closely back together he could then discharge it. If that's true, how
could the charge be stored in the air separating the two, especially when
the air was circulating, which I'm sure it was? Maybe it was because it was
a static charge, like we get in the winter from walking on carpet. I guess
I'll have to look back at his experiments.

Jim

"J. Pinkston",

Correct me if I'm wrong, but didn't Ben Franklin,

I think Ben's only static generator was out of service when it wasn't raining.
The first capacitors were called Leyden jars, I think that's the name of the
town were they were invented. Even though I taught electronics for seventeen
years we unfortunately had to skip over the wonderful stories of discovery that
used to be part of such courses. They could be inspirational and spark (pardon
the pun) the student's interest because they were about the real world. I can't
even think of which country the town of Leyden is in. I do know that one of the
showmen of electricity was a guy called Michael Faraday. I know he was a showman
because the most often shows him in a very showmanship like pose. Anyway, the
unit of capacitance was named after him, the Farad is one gigantic unit. The
largest capacitor I've seen in terms of capacitance was in the hundreds of
thousands of micro farads. Or say 0.1 to 0.2 Farads.

Maybe it was because it was a static charge, like we get in the winter from
walking on carpet. I guess I'll have to look back at his experiments.

Exactly, and a charge can only accumulate on/in an insulator.

Jim

When I was reading your reply I saw the name at the end and said, Hey, I didn't
say that.

Jim

I'd like to know, myself, why people think that the charge is stored in the dielectric. It's stored on the plates, the dielectric just facilitates electron transfer.

-Mike

From: "J. Pinkston" <pinkston@...>
Reply-To: Electronics_101@...
To: <Electronics_101@...>
Subject: Re: [Electronics_101] Digest Number 134
Date: Sun, 28 Oct 2001 17:53:45 -0600

Correct me if I'm wrong, but didn't Ben Franklin, when he was doing his
experiments with electricity, put to plates close together hooked up to his
static generator, & charge them? That part I'm pretty sure is true. But it
seems like he then could take one of the plates away for a while & when he
put it closely back together he could then discharge it. If that's true, how
could the charge be stored in the air separating the two, especially when
the air was circulating, which I'm sure it was? Maybe it was because it was
a static charge, like we get in the winter from walking on carpet. I guess
I'll have to look back at his experiments.

Jim

________________________________________________________________________

Message: 9
Date: Sat, 27 Oct 2001 17:47:10 -0500
From: Jim Purcell <jpurcell@...>
Subject: Re: Re: Fuses vs. resistors

Guillermo,

it's stored in vacuum capacitors.

That's a good one! I would be very grateful if you tell me the

Have to get it from someone besides me. I'm neither a physicist,
nor an engineer, although I challenge an engineer to explain it. :-)

Jim

_________________________________________________________________
Get your FREE download of MSN Explorer at

I do know that one of the
showmen of electricity was a guy called Michael Faraday.

Ah, yes, the inventor of the dynamo.

From: Jim Purcell <jpurcell@...>
Reply-To: Electronics_101@...
To: Electronics_101@...
Subject: Re: [Electronics_101] Digest Number 134
Date: Sun, 28 Oct 2001 20:43:51 -0600

"J. Pinkston",

Correct me if I'm wrong, but didn't Ben Franklin,

I think Ben's only static generator was out of service when it wasn't raining.
The first capacitors were called Leyden jars, I think that's the name of the
town were they were invented. Even though I taught electronics for seventeen
years we unfortunately had to skip over the wonderful stories of discovery that
used to be part of such courses. They could be inspirational and spark (pardon
the pun) the student's interest because they were about the real world. I can't
even think of which country the town of Leyden is in. I do know that one of the
showmen of electricity was a guy called Michael Faraday. I know he was a showman
because the most often shows him in a very showmanship like pose. Anyway, the
unit of capacitance was named after him, the Farad is one gigantic unit. The
largest capacitor I've seen in terms of capacitance was in the hundreds of
thousands of micro farads. Or say 0.1 to 0.2 Farads.

Maybe it was because it was a static charge, like we get in the winter

from

walking on carpet. I guess I'll have to look back at his experiments.

Exactly, and a charge can only accumulate on/in an insulator.

Jim

When I was reading your reply I saw the name at the end and said, Hey, I didn't
say that.

Jim

_________________________________________________________________
Get your FREE download of MSN Explorer at

开云体育

d,

I'd like to know, myself, why people think that the charge is stored in the
dielectric. It's stored on the plates, the dielectric just facilitates
electron transfer.

Sorry, but the charge is stored in the dielectric. That's why the amount of
capacitance depends in part on the kind of dielectric. A conductor will not
store a charge, only provide a path for it. Insulators respond to the potential
difference and the atoms get distorted in the sense that some lose or gain
electrons. Any imbalance in the atoms of a conductor equalizes when the current
stops, not so with insulators. The fact that I can't see how a vacuum stores a
charge doesn't alter the fact that it is the dielectric that stores the charge.

Jim

Himont,

As some-one has already suggested that charge is stored on the plates and that the dielectrics is a medium for the charge transfer...

Nope!?Well may be the use of vaccum capacitors is because of least dielectrics so that breakdown voltage is high... but this has a trade-off that the capactiance would be low...

But this is also so of air capacitors, but both are used at higher frequencies where low capacitance is less important than having a self healing dielectric. Of course there are limits even to this trait. I once had to replace some really large air dielectric capacitors in a radio transmitters that had been victims of ball lightening. It danced between the plates and literally fuzed some of them together.

Jim

开云体育

Jim,

Dammit, now I HAVE to look this up. Thanks.

-Mike

From: Jim Purcell <jpurcell@...>
Reply-To: Electronics_101@...
To: Electronics_101@...
Subject: Re: [Electronics_101] Digest Number 134
Date: Mon, 29 Oct 2001 10:29:40 -0600

d,

I'd like to know, myself, why people think that the charge is stored in

the

dielectric. It's stored on the plates, the dielectric just facilitates
electron transfer.

Sorry, but the charge is stored in the dielectric. That's why the amount of
capacitance depends in part on the kind of dielectric. A conductor will not
store a charge, only provide a path for it. Insulators respond to the potential
difference and the atoms get distorted in the sense that some lose or gain
electrons. Any imbalance in the atoms of a conductor equalizes when the current
stops, not so with insulators. The fact that I can't see how a vacuum stores a
charge doesn't alter the fact that it is the dielectric that stores the charge.

Jim

_________________________________________________________________
Get your FREE download of MSN Explorer at

--- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote:.

Sorry, but the charge is stored in the dielectric. That's why the

amount of

capacitance depends in part on the kind of dielectric. A conductor

will not

store a charge, only provide a path for it. Insulators respond to

the potential


Jim, My understanding of the capacitor is that the actual electron
are stored on the plate, or conductor. The closer you can get them
together (meaning a thinner and less conductive dielectric), the more
force they exert on each other. Both parts are involved, but the
charge is on the plates.
Rex

"Mr.",

My understanding of the capacitor is that the actual electron
are stored on the plate, or conductor.

Is that a derived understanding or does it come from a direct
statement made by someone who knows.?

The closer you can get them
together (meaning a thinner and less conductive dielectric),

The dielectric doesn't conduct, that's why it's also called
an insulator. The reason for greater capacitance when the
dielectric is thinner is that there is less distance through
which the charge has to act. A conductor just cannot be
charged. It's electrons are free and will not be permanently
removed or added to it's atoms. Because insulators not not
easily give up or accept electrons, once they do they stay
that way. At least until a path is provided for things to
neutralize or even to become charged with the opposite
polarity.

force they exert on each other. Both parts are involved, but the
charge is on the plates.

Nope. The part the plates play is their size, large plates involve more
dielectric surface area to the potential difference that charged it.
As does larger plate area.

Jim

Date: Mon, 29 Oct 2001 10:29:40 -0600
From: Jim Purcell <jpurcell@...>
Subject: Re: Digest Number 134

d,

I'd like to know, myself, why people think that the charge is stored in

the

dielectric. It's stored on the plates, the dielectric just facilitates
electron transfer.

Sorry, but the charge is stored in the dielectric. That's why the amount

of

capacitance depends in part on the kind of dielectric. A conductor will

not

store a charge, only provide a path for it. Insulators respond to the

potential

difference and the atoms get distorted in the sense that some lose or gain
electrons. Any imbalance in the atoms of a conductor equalizes when the

current

stops, not so with insulators. The fact that I can't see how a vacuum

stores a

charge doesn't alter the fact that it is the dielectric that stores the

charge.

Jim

My idea would be that the charge is stored in the electric field.
This is enabled equally by the positive plate which gave up electrons and
the negative plate which has an excess, a condition that would like a
current to flow, but is prevented by the dielectric. Various types of
dielectrics have different dielectric constants which would dictate the
thickness or distance between plates to achieve the same result when
comparing different types of dielectrics.

The first poster says a dielectric "facilitates" electron transfer.
It actually inhibits it. To facilitate would make it a conductor, and there
would be no charge.

mike g.