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Author Topic: Can be a capacitor charged using a electron source?  (Read 5076 times)

Offline sorincosofret

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Can be a capacitor charged using a electron source?

Experimental part
 The present study put in evidence different comportment of a capacitor when is connected to   various sources of ,,electric current”.
In this example is important to underline the difference between a Van der Graff device and a cathode ray tube. The complete experiment is presented in the book.

A capacitor bought from market (fig. 1), was tested previously, measuring the capacitance and testing the eventually short circuits between plates.




Fig. 1

The second capacitor (fig. 2) was home made using aluminum kitchen foil of about 2 m long and polyethylene foil as dielectric.  The plates with the dielectric inside are rolled on and a compact but powerful capacitor is obtained.



Figure 2.

As it can be seen, both capacitors are valid; their resistance is infinite ( in electronic jargon). Both capacitors when charged with a normal  DC source are able to produce sparks of minim 1 cm length.

In a first series of experiments any capacitor is connected with a single plate to a CRT , respectively to a  brush from VDG device. The other plate of capacitor remains free. In order to avoid CRT or VDG interferences, the distance between capacitor and ,,current source “ was set up to about 2 m.
The results are disconcerting.
Having the capacitor connected to a modified CRT ( fig 3)-as was described in previous posts-, when a gas tube  is positioned close to plate 1 or plate 2, no light flash is observed



Figure 3


In case of a Van der Graff device (fig. 4), with the same experiment configuration, if the gas tube is fixed either close to contact of  plate 1 or either on plate 2, the flickering of tube is observed. There is no difference of flickering between plate 1 and 2. Even after one hour, a capacitor close to plate 2 is still flickering with the same intensity like at beginning.



Figure 4


If the capacitor is connected to the other brush (fig.5)  the same results are obtained.




Figure 5

The representation of VDG respects the actual accepted charge movements and distribution. 
As was already described the CRT is more powerful then VDG device.  CRT can deliver 3,5 micro A and VDG  maxim of 2.5 micro A. 
How can be interpreted this result?

As supplementary help for those who are interested to explain this experiment, the comportment of capacitor in a little bit modified experiment is presented.
First the discharge current of CRT tube is measured, related to a null point (house heating system).



After that the capacitor is introduced in circuit. The main points to be followed regard the variation of current intensity during charging.   




 In the experiment, no variation of capacitor charge electric current was observed in time. The current passing through capacitor is about 80 percent from ,,current“ delivered by CRT.  In absence of capacitor the current in circuit was about 7 micro A using a new CRT tube recovered from a color monitor. In the presence of capacitor the current intensity oscillate between 5,5 and 6.5 micro A.
The experiment was repeated with smaller, commercial capacitor. The results are the same. A capacitor does not charge in presence of an electric charge source, and leave the current to pass through it.

« Last Edit: 06/11/2008 05:01:41 by sorincosofret »


 

Offline Bored chemist

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Can be a capacitor charged using a electron source?
« Reply #1 on: 06/11/2008 06:57:12 »
Welcome to the world of leakage currents.
 

lyner

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Can be a capacitor charged using a electron source?
« Reply #2 on: 06/11/2008 07:25:38 »
What is a 'powerful capacitor' supposed to be?
Can you have a powerful piece of wood or a powerful stone?
A capacitor can have capacity and a maximum operating voltage.
If you want to give us Science lessons then get the basics right. The words have specific meanings.

 

Offline sorincosofret

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Can be a capacitor charged using a electron source?
« Reply #3 on: 06/11/2008 07:49:47 »
Thanks for the wishes!
We are not in the XIX century when a micro or pico current was a problem to be measured. The effects of smaller VDG device are evident in comparison with greater currents coming from CRT.
Of course, in the entire world there are more powerful sources of electrons instead of a TV CRT, and greater VDG too. The effect and the conclusion will be the same.
Remain the simple problem of interpretation.
I avoid to give capacities. I'm not sure that the term capacities is ,,right" for describing the capacitor comportment. Because as will be seen in the future experiments other contradiction appear.
So I appreciate the ,,power" of a capacitor after length of flash when the capacitor is put in shortcircuit.
 

lyner

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Can be a capacitor charged using a electron source?
« Reply #4 on: 06/11/2008 15:09:37 »
From your explanation, you clearly mean 'capacity', not 'power'. That is the amount of charge that is stored per volt. Why avoid the correct term when it exists?
Another point is that we don't really have 'sources of electrons'. The Crt and everything else merely circulates electrons at high energy. Once they reach the positive end, they return to Earth and find their way round to the Cathode again, eventually. Like I said earlier, if you pile charge in one place, very soon the voltage (and the attractive force) will be so high that electrons will flow via another path (breakdown) or the structure will collapse.
 

Offline sorincosofret

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Can be a capacitor charged using a electron source?
« Reply #5 on: 06/11/2008 15:44:41 »
A capacitor does not charge due to a apparition of opposite and equal charges on the plates. Therefore ,,capacity" need a redefinition or it is necessary other term.
The CRT  with presented improvements circulate electrons at very moderate energies. When these electrons heat the screen, they loose the kinetic energies and after that they run into the metallic conductor at speed of  mm per second. Is the same process like in the post related to diode and its principle. Look again at the post.   Why in my case the electrons run in the metallic conductor at high speeds?
Between CRT and capacitor there are 2 m of metallic conductor.
If the electron movement does not represent a flow of electricity, what is measuring the ammeter?
Please make a picture of the flow of electrons in the circuit.....

 
 

lyner

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Can be a capacitor charged using a electron source?
« Reply #6 on: 06/11/2008 17:36:29 »
Quote
A capacitor does not charge due to a apparition of opposite and equal charges on the plates. Therefore ,,capacity" need a redefinition or it is necessary other term
Do you actually know anything at all? If it doesn't do that then what does it do?
Of course, the charge is actually distributed all over the circuit but the potential gradient across the plates is so much higher that you can treat the charge as being on the plates.

Quote
The CRT  with presented improvements circulate electrons at very moderate energies. When these electrons heat the screen, they lose the kinetic energies and after that they run into the metallic conductor at speed of  mm per second.
The 'power source' gives electrons their total energy (eV) which is transfered as they go round the circuit. Total energy given to each electron is total energy expended by the electron on the way around. You must realise that the number of charge carriers in the electron beam is much lower than the number which are moving in the solid metal.

Quote
Why in my case the electrons run in the metallic conductor at high speeds?

what makes you think that they do?

Quote
Please make a picture of the flow of electrons in the circuit.....
Look at an elementary School Science Book. They get that right, at least.
If they don't flow round, where do they go?
Sometimes your ignorance amazes me. Learn some basics before you make yourself look so foolish.



« Last Edit: 06/11/2008 21:07:32 by sophiecentaur »
 

Offline Bored chemist

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Can be a capacitor charged using a electron source?
« Reply #7 on: 06/11/2008 19:58:34 »
"We are not in the XIX century when a micro or pico current was a problem to be measured."
In reality, rather than Sorin's imagination, they were perfectly capable of measuring pico amp currents back then.

As I mentioned earlier, no cpapcitor is perfect. They leak. The setup for measuring the leakage current in a capacitor is not unlike that in Sorrin's last diagram.
For some reason he thinks this is news to the scientific community.
 

Offline sorincosofret

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Can be a capacitor charged using a electron source?
« Reply #8 on: 07/11/2008 04:41:22 »
Of course, the charge is actually distributed all over the circuit but the potential gradient across the plates is so much higher that you can treat the charge as being on the plates.

This is only your imagination.....

The 'power source' gives electrons their total energy (eV) which is transfered as they go round the circuit. Total energy given to each electron is total energy expended by the electron on the way around. You must realise that the number of charge carriers in the electron beam is much lower than the number which are moving in the solid metal.

The number of charge carrier should be the same in electron beam and in the metallic conductor. The number of charge (positive an negative is greater in metallic conductor than in the CRT). Your ignorance and stupidity make me cry. Go on and read low level physics books and after that make comments. It is outrages absurd that a number of electrons are moving in a part of circuit and after that a greater number in another part.

As I mentioned earlier, no capacitor is perfect. They leak. The setup for measuring the leakage current in a capacitor is not unlike that in Sorrin's last diagram.
For some reason he thinks this is news to the scientific community.


The leak should be related to the intensity of current. Why in the case of VDG with a lower current the effects are visible and in the case of CRT all charge is loss, even the intensity in case of CRT is two times greater?
I'm agree that any electronic circuit has leaks. So it is possible to have a leak of 30 maybe 50 percent of current. In this case a remaining current of 1 micro A in case of VDG has visual effects and a remaining current of 3 microA in case of CRT does not have any effect
 

lyner

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Can be a capacitor charged using a electron source?
« Reply #9 on: 07/11/2008 10:38:34 »
Quote
It is outrages absurd that a number of electrons are moving in a part of circuit and after that a greater number in another part.
Here is an analogy.
Imagine a huge meeting hall with a corridor joining each end. One person runs down the corridor and enters the room and one person leaves the other end and runs around to the entrance. A thousand people in the meeting move slightly towards the exit to allow this to happen. Two people have moved in the corridors. Can you see the parallel?
Otherwise:
Look in a Physics textbook for the formula involving speed of flow, charge density and current.
Then use your brain.

Quote
A in case of VDG has visual effects and a remaining current of 3 microA in case of CRT does not have any effect
Do you have any idea of the difference between the voltages involved in each of your examples?
Another nonsense comment, I'm afraid.
« Last Edit: 07/11/2008 10:42:28 by sophiecentaur »
 

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Can be a capacitor charged using a electron source?
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