Resistance of capacitor

[studiot]

I don't believe I mentioned the phrase 'charge field'.

 

Where did that come from, and what do you think it means?

 

There is no energy associated with the field generated by a single charge.

Try reading this bit again.

 

 

Energy due to the interaction between a charge and another charge or charges

 

I have no idea what you mean by 'a separate field' either.

[hoola]

I mean an amount of the total energy (as charge field) being the mechanism that allows the 2 plates to "see" each other...and afford the relationship that allows a charge between proximate plates to exist...certainly an electron has a charge field. It would seem the charge field would collapse back into the negative plate upon discharge, returning the energy that was used to create this field...

Edited November 1, 2014 by hoola

[fiveworlds]

In an AC circuit the capacitors resistance is called 'Impedance' and is calculated from the following formula: xc=1/2(pi)(F)(C )

Where F is the frequency in Herz (Hz) and C the capacitance in Farads. The resistance of a capacitor is also dependent on if the current is ac or dc

Edited November 1, 2014 by fiveworlds

[studiot]

 

...and afford the relationship that allows a charge between proximate plates to exist

 

I am getting bored with this constant repetition of your false statement that there is charge between the plates of a capacitor.

 

Since this is contrary to conventional thinking, please prove your words.

[fiveworlds]

there is charge between the plates of a capacitor.

 

Lightning van de graff generator

Edited November 1, 2014 by fiveworlds

[studiot]

When the spark current is flowing the arrangement is no longer a capacitor.

 

It is actually doubtful if the arrangement can be considered a capacitor even before the points are brought close enough to generate a spark.

This is because the capacitance is proportional to the cross section area and you have shown tapering points, which in the limit tend to zero area, and therefore zero capacitance.

[fiveworlds]

When the spark current is flowing the arrangement is no longer a capacitor.

 

Why not?

[Strange]

Why not?

 

See post 31 for a detailed explanation.

I mean an amount of the total energy (as charge field) being the mechanism that allows the 2 plates to "see" each other...and afford the relationship that allows a charge between proximate plates to exist...certainly an electron has a charge field. It would seem the charge field would collapse back into the negative plate upon discharge, returning the energy that was used to create this field...

 

There is no such thing as a "charge field". The plates cannot see each other. There is no charge between the plates.

[fiveworlds]

tend to zero area, and therefore zero capacitance.

 

It isn't zero area

brought close enough to generate a spark.

 

There is no limit on range that I know of.

When the spark current is flowing the arrangement is no longer a capacitor.

 

The capacitor has not stopped storing current only the electrons with enough energy to bridge the gap actually move.

[Strange]

It isn't zero area

 

He didn't say it is. "Tends..."

 

There is no limit on range that I know of.

 

Of course there is. (Although, again, he didn't say there was a limit on the range.)

 

The capacitor has not stopped storing current only the electrons with enough energy to bridge the gap actually move.

 

Once the dielectric breaks down it is a conductor and therefore the arrangement is no longer a capacitor.

 

Following your usual pattern, I now predict you will drag up a series of increasingly irrelevant references rather than admit you might have made a mistake.

[fiveworlds]

Once the dielectric breaks down it is a conductor

 

No it only conducts the electrons that have sufficient energy. In doing so they lose energy to the dielectric which in this case causes the dielectric to emit light. We know this because the light comes from atoms dropping down an energy level with the release of energy. Actually there's a good question will a van de graff generator in a vacuum still emit light? Though you can tell me what corona discharge is.

 

Following your usual pattern, I now predict you will drag up a series of increasingly irrelevant references rather than admit you might have made a mistake.

 

Not fair I hate referencing I was only doing so because I was informed I had to. The whole idea that seeing information on the internet and then using that information ie. copying that information being wrong is completely foreign to me especially since I cannot afford to go learn these things myself and using the internet is the one of the few times I get to learn anything at all. Though in actuality the only real reason for referencing that I would adhere to is in relation to health studies. If I gather a load of figures and statistics from databases on the number of smokers in an area then I need to inform people where I got my information from if I wasn't the one performing the survey. Then again I see self-plagiarism i.e. copying yourself and go these people are insane. More to the point because making a new edition of a textbook would be classified as self-plaigiarism.

Edited November 2, 2014 by fiveworlds

[hoola]

so an electron has no charge field, only a self-contained charge ?

Edited November 2, 2014 by hoola

[Mike Smith Cosmos]

It is interesting , this whole ( not hole) , subject of the movement and positioning of electrons about a substance ( insulator ,like a balloon , rubber, dielectric ,) and a conductor ( wire, gold leaf , plate in a capacitor ) . One thinks of flow of electrons being together . Yet electrons in some respect want to get away from each other . ( similar charges REPEL ) .

That is possibly why they spread out across the surface of the plates in a capacitor. And why they spread out across the gold leaf in a ' gold leaf electroscope ' and the leaves of gold separate to indicate the presence of a charge.

Also in a different medium , like a rubber balloon , rubbed on your jumper ( rubber being an insulator like a dielectric ) , has electrons spread out across its surface , so as to make small pieces of paper to jump up to the balloon. Yet .

 

The electrons in a wire conductor or plate are in such a state as to their outer energy bands to be overlapping or very adjacent so as to allow free movement ( without requiring much additional energy ,to move ) , in their conduction band. This enabling them to move easily across the conducting wire or plate. Whereas the electrons in a balloon or dialectric , in their outer energy bands , are not free to move about ( no conduction band ) or at least or requires much, much more energy to reach a conduction band , or conducting condition .

 

It is also interesting that electrons , do not individually move very fast in a conductor ( approx walking speed 3 mph ) it is their effect that moves at nearly the speed of light ! Thus the effect of an individual electron can move about a capacitor plate at nearly the speed of light , but the individual electron or HOLE ( + electric charge absence of electron ) moves fairly slowly approx walking speed 3 mph about the capacitor plate . Although having said that a ' hole' is an effect , as there is nothing actually there [ hole being the absence of an electron ], where there is actually something there in an electron. Humm ! Maybe it is the charge that moves as an effect ! In that case the effect could move at nearly the speed of light , but not the individual electron .

 

You put one electron ( individual electron ) into one end of a conductor ( say a mile long ) , it would be moving physically at 3 mph slowly . Yet it's value of charge would be communicated to the other end of the wire, say a mile away , or conductor at nearly the speed of light . In other words particle like electrons move about with mass relatively slowly in this classical world and effects like photons with no mass move about at the speed of light as an effect in the quantum world . This is your wave - particle duality rearing its head .

 

It would appear from what I have reasoned above , " Nobody is going anywhere fast, but their effect communicated by the change in charge , is going somewhere fast "

 

( where not fast = 3miles per hour , and fast is approximately the speed of light ) .

 

Mike

 

Ps . The whole ( not hole ) subject has immense relevance for power generation and transmission and for that matter electro magnetic radiation . ( and transmission ) . But that is several orders of magnitude away from capacitor plates . However it has to be said the issues are exactly the same . We pump electrons into an antenna or transmission line in ( " Shedloads of electrons , then back in the other direction in Shedloads , many times a second , with a great deal of giggery pokery" ) . And miracle upon miracle the EFFECT . or Photon ( photons equally in Shedloads ) scoots off at the speed of light .

 

Wow ! That's why I studied electrical, electronics and satellite communications at UNI. Not that anybody is any clearer " what quite is going on ?

Edited November 2, 2014 by Mike Smith Cosmos

[Strange]

so an electron has no charge field, only a self-contained charge ?

 

I assume you mean electric field?

[studiot]

 

hoola

so an electron has no charge field, only a self-contained charge ?

 

 

This thread provides an excellent opportunity to clear up some misunderstandings of basic terms such as a field.

 

An electron has no 'charge field'.

 

This thread is about Physics so we neeed the physics definition of a field.

 

In Physics, a field is a region of space where we can assign a finite value of some variable of interest to every point.

 

Note this value must be finite, although it may be zero, and available at every point.

Further we require that the change of values of this quantity from one point to the enxt is smooth or continuous.

Some physical agent is required to create a discontinuity in a field.

 

Think of a river.

Every point in the flowing water has a water density, and every small parcel of water around that point has a mass.

 

This (mass) would be analagous to a charge field if the charge were smeared out over the whole region of space.

But charge is not smeared out, it is concentrated in particles (electrons in this case).

 

We could address this by have largely zero values in our field, but we would still be left with discontinuities as we regard electrons as point particles at this level of analysis.

 

So instead of talking about a charge field' we talsk about a charge distribution when we have more than one charge to discuss.

 

If you are happy with this and want me to explain how this applies to a capacitor, I will be happy to do so.

 

 

fiveworlds

Why not?

Posted Today, 01:18 AM

Quote

Once the dielectric breaks down it is a conductor

 

No it only conducts the electrons that have sufficient energy. In doing so they lose energy to the dielectric which in this case causes the dielectric to emit light. We know this because the light comes from atoms dropping down an energy level with the release of energy. Actually there's a good question will a van de graff generator in a vacuum still emit light? Though you can tell me what corona discharge is.

 

 

Strange correctly understood what I was saying.

 

The underlined part is true of all conductors, That is where the conduction electrons come from.

These electrons only move when the applied voltage (did you forget that?) is large enough. That is where the energy comes from.

Of course enough voltage to create the spark will have to be applied (I have already said that before) and , by definition all these electrons will have enough energy.

You can reduce this by thermionic emission of course, (and study your question about light emission in a vacuum to boot).

 

BUT

 

The region between the conductors then becomes a conductor with measurable conductance (resistance) which, by definition, is no longer a dielectric.

 

Dielectrics, by definition, do not conduct electricity.

[hoola]

yes, an electric field of negative potential = the "charge field" of an electron in my usage...

[Strange]

Actually there's a good question will a van de graff generator in a vacuum still emit light?

 

No. The light comes from the ionized gas.

 

Not fair I hate referencing I was only doing so because I was informed I had to. The whole idea that seeing information on the internet and then using that information ie. copying that information being wrong

 

It is not the referencing or copying information that I was objecting to, it is the increasingly irrelevant and desperate objections that you bring up to defend your erroneous positions. You have already dragged this thread off topic by bringing up spark gaps, coronal discharge, etc. So lets leave it there.

[studiot]

 

yes, an electric field of negative potential = the "charge field" of an electron in my usage...

 

 

If that was an answer to my post I am obviously wasting my time trying to help.

[Mike Smith Cosmos]

That is possibly why they spread out across the surface of the plates in a capacitor. And why they spread out across the gold leaf in a ' gold leaf electroscope ' and the leaves of gold separate to indicate the presence of a charge.

 

The electrons in a wire conductor or plate are in such a state as to their outer energy bands to be overlapping or very adjacent so as to allow free movement ( without requiring much additional energy ,to move ) , in their conduction band. This enabling them to move easily across the conducting wire or plate. Whereas the electrons in a balloon or dialectric , in their outer energy bands , are not free to move about ( no conduction band ) or at least or requires much, much more energy to reach a conduction band , or conducting condition .

 

. We pump electrons into an antenna or transmission line in ( " Shedloads of electrons , then back in the other direction in Shedloads , many times a second . And miracle upon miracle the EFFECT . or Photon ( photons equally in Shedloads ) goes off at the speed of light .

 

 

 

Change in Electrical Charge and change in magnetic flux at sufficient frequency in a Capacitor - Induction Coil assembly , connected to an antenna , can cause Photons of E-M waves to move away at the Speed of Light

 

E=M Waves link :- https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwww.rmcybernetics.com%2Fscience%2Fphysics%2Felectromagnetism_intro_electromagnetic_waves.htm&ei=bWZZVPbWNcLVaqDYgvgH&bvm=bv.78677474,d.d2s&psig=AFQjCNEIA3gLOxCW1lAVd0dYBqHOXq12VA&ust=1415231440851398

Courtesy of Nasa

 

Mike

Edited November 4, 2014 by Mike Smith Cosmos

[knyazik]

 

Change in Electrical Charge and change in magnetic flux at sufficient frequency in a Capacitor - Induction Coil assembly , connected to an antenna , can cause Photons of E-M waves to move away at the Speed of Light

 

E=M Waves link :- https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwww.rmcybernetics.com%2Fscience%2Fphysics%2Felectromagnetism_intro_electromagnetic_waves.htm&ei=bWZZVPbWNcLVaqDYgvgH&bvm=bv.78677474,d.d2s&psig=AFQjCNEIA3gLOxCW1lAVd0dYBqHOXq12VA&ust=1415231440851398

Courtesy of Nasa

 

Mike

So what does this mean as far as the resistance of a capacitor? Is there some sort of periodic effect that you're identifying?

[Mike Smith Cosmos]

So what does this mean as far as the resistance of a capacitor? Is there some sort of periodic effect that you're identifying?

 

The functioning of a capacitor is radically different when working in the different modes Direct Current ( DC ) and Alternating Current (AC)

 

DC . can be a storage of Charge, stabilizing a voltage level . Internal resistance will affect the rise and fall time of the voltage level

 

AC . The capacitor can be used to conduct a signal (ac) from place to place while offering DC isolation. Also and possibly its most intriguing, It can be used in AC mode in connection with a coil or inductance to produce a resonant or oscillating Signal .Here the internal resistance of both the capacitor and coil can effect the 'Q' of the combination. . This is a sort of gain or efficiency of the combination , which if very high 'Q' in of value, and is very useful . Used in transmission of Radio waves across vast distances.

 

Mike

Edited November 7, 2014 by Mike Smith Cosmos

[Mike Smith Cosmos]

The Transmission of Radio Frequencies is often accomplished by a Capacitor Coil combination, as the Driver of an Antenna .

The following link illustrates various circuits where a COIL and CAPACITOR in various combination appears next to the Antenna. ( symbol V with center I .) . Some of the circuits are Audio Frequency so do not apply /

 

Link : - https://www.google.co.uk/search?q=Power+Amplifier+Transmission+circuit&rlz=1C1RNNN_enGB356&espv=2&biw=1198&bih=642&tbm=isch&tbo=u&source=univ&sa=X&ei=OOZfVNyrLrGM7AbgvYDwAQ&ved=0CCsQ7Ak

 

Example .Of a Radio Frequency Output stage to an Antenna,

using Coil and Capacitor combination ( resonant, Tuned High ' Q Low resistance in L,C Circuit )

 

 

 

Mike

Edited November 9, 2014 by Mike Smith Cosmos

[david345]

With an ac circuit the capacitor will act like a resistor. If the circuit has only a resistor then current is l=E/R. If it has only a capacitor then I=E/Xc. Xc is capacitive reactance Xc=1/(2pifc). Pi is the number. F is frequency. C is capacitance. Xc is measured in ohms just like resistance. If there is a resistor and capacitor in series then I = E/Z. Z is impedance. Z= sqrt ( R^2+Xc^2). With a dc circuit when the capacitor is charged current flow stops. The resistance would be that of the dielectric between the plates. With enough voltage you could short the capacitor. Current would flow through the shorted capacitor and the shorted capacitor would have some resistance.

Edited November 10, 2014 by david345

[Mike Smith Cosmos]

The relevant components in the transmission device or circuit above ,are primarily the ( L. Coil, Inductance, having a magnetic field ) and the ( C ,capacitor, having an electric field engendered between its plates in a dielectric ) and the antenna ( making the oscillating E-M electro magnetic fields head out into space ) .

The need for resistance to be low in both the capacitor and coil is so that the oscillations can be large( not damped ) .

Useful analogies ( models) are
1. A wine glass being held tight to a table, empty, and gently rubbing your damp finger around the rim. Get it right and it will sing like a canary.
2. Stroke a violin bow across the centre of the string of a violin , and enchant the audience.
3. Hit the loose end of a tuning fork , and place on a wooden table and hear the note. ( and probably just scratched your dining room table. )

Each has a ground , to work from , and free loose ends to vibrate or oscillate .

In the case of the coil and capacitor , the power supply end , and the earth rail at the bottom act as the fixed ground state to work from . Somewhere in the coil capacitor combination an oscillating electrical and magnetic field is vibrating at millions of times a second. ( like the vibrating wine glass but you cannot see it. If you can capture this , and send it to an antenna and the area around the antenna, you can send this oscillating E-M field away into space at the speed of light. That is the miracle.

To make this process be efficient you need the resistance to be very low in the capacitor, and in the inductor.

Big ,thick copper pipes( coil) and aluminium plates (capacitor) . In the older BBC transmitting stations these two components looked more like household plumbing water pipes , and sheets of aluminium. Nowadays you are probably thinking more of resonant cavities in a magnetron , like a microwave oven has in it. These are Not good to experiment with or you will cook yourself. But a coil and a capacitor can be great fun. Keep it small power or you will cause interference.

You will note the driver ,in the circuit ( a transistor giving a signal frequency ) , this being equivalent to your finger on the wine glass. This supplies the small seeding oscillation to make the high Q ( coil and capacitor with low resistance ) , sing like a parade day lone trumpeter playing a single note into the sky and hills beyond !



Mike

Ps For long distance experiments. You will need a licence.......... Not for blowing a trumpet !

Edited November 10, 2014 by Mike Smith Cosmos

[knyazik]

The relevant components in the transmission device or circuit above ,are primarily the ( L. Coil, Inductance, having a magnetic field ) and the ( C ,capacitor, having an electric field engendered between its plates in a dielectric ) and the antenna ( making the oscillating E-M electro magnetic fields head out into space ) .

 

The need for resistance to be low in both the capacitor and coil is so that the oscillations can be large( not damped ) .

 

Useful analogies ( models) are

1. A wine glass being held tight to a table, empty, and gently rubbing your damp finger around the rim. Get it right and it will sing like a canary.

2. Stroke a violin bow across the centre of the string of a violin , and enchant the audience.

3. Hit the loose end of a tuning fork , and place on a wooden table and hear the note. ( and probably just scratched your dining room table. )

 

Each has a ground , to work from , and free loose ends to vibrate or oscillate .

 

In the case of the coil and capacitor , the power supply end , and the earth rail at the bottom act as the fixed ground state to work from . Somewhere in the coil capacitor combination an oscillating electrical and magnetic field is vibrating at millions of times a second. ( like the vibrating wine glass but you cannot see it. If you can capture this , and send it to an antenna and the area around the antenna, you can send this oscillating E-M field away into space at the speed of light. That is the miracle.

 

To make this process be efficient you need the resistance to be very low in the capacitor, and in the inductor.

 

Big ,thick copper pipes( coil) and aluminium plates (capacitor) . In the older BBC transmitting stations these two components looked more like household plumbing water pipes , and sheets of aluminium. Nowadays you are probably thinking more of resonant cavities in a magnetron , like a microwave oven has in it. These are Not good to experiment with or you will cook yourself. But a coil and a capacitor can be great fun. Keep it small power or you will cause interference.

 

You will note the driver ,in the circuit ( a transistor giving a signal frequency ) , this being equivalent to your finger on the wine glass. This supplies the small seeding oscillation to make the high Q ( coil and capacitor with low resistance ) , sing like a parade day lone trumpeter playing a single note into the sky and hills beyond !

 

image.jpg

 

Mike

 

Ps For long distance experiments. You will need a licence.......... Not for blowing a trumpet !

Love the drawings. My friend in High School installed a 1 Farad capacitor in his car. Took up all his trunk, and really amplified his base. Not only was it a extreme base, but also when he did connect the capacitor his car would shake violently, and his headlights would go dim.