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Registered Member #1379
Joined: Thu Mar 06 2008, 09:49AM
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Posts: 7
Just a quick idea that has been hurting and tormenting my already bruised mind for the last month:
1.) Does the electrical conductance correlate with charge holding? IE: A bucket of salt water vs a roll of copper. If they both had the same weight regardless of any other factors which could "hold" the most charge?
2.) Does the ionisation of a substance improve its ability to capacitate? IE: As in a battery but convert it to a capacitor: One plate ph1 other ph14 (strong acid/alkaline)
Does anyone think it possible to overcome the electrostatic charge boundary (ie the distance electrostatic opposition travels) to create for example a salt water capacitor that is far superior to a electrolytic capacitor with hundreds of windings?
As i said just an idea. I haven't got the science even close to perfected. Just another idea I have which annoys me.
Registered Member #350
Joined: Mon Mar 27 2006, 05:14PM
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Posts: 106
The capacity doesn't depend on the conductance. You can fill a plastic bucket with water and put aluminum foil at the outside. But you could also put aluminum foil inside and outside and use no water at all. In both cases you get the same capacity. The capacity depends on the area of the metal plates/metal foil, etc. and on the thickness of the dielectricum. The dielectricum is the material that's between the two metal plates e.g. the plastic wall of the bucket, The bigger the area and the thinner the dielectricum the higher the capacity. Ions don't play any role here. The energy of a capacitor is actually stored in the electric field. That means it's stored inside the dielectricum. So the maximum energy a capacitor can store depends on the volume of the dielectricum and on the maximum field strength. If you use a bucket you have a large volume but most of that is empty. Only the volume of the plastic wall is filled with an electric field and so only there energy is stored. So most of the volume of the bucket is just wasted space.
Registered Member #1379
Joined: Thu Mar 06 2008, 09:49AM
Location:
Posts: 7
Yes that is 100% correct. It is interesting that the main advances in capacitors has been better insulators so one gets closer proximity to the plates.
Is there anyway to contain the field and stretch it so it affects a greater distance?
Somehow similar to stretching a magnetic field? I have some super magnets that effect each other from over 2 metres away...
This reminds me of a freak incident years ago. I was playing around with a PSU from a computer it was switched on and had no cover so the live parts were exposed. I decided to run this super magnet over the 400+ pf 250v twin electrolytic (DC) capacitors. I was holding the metal on the screwdriver which had the super magnet stuck to it and it did not touch the live or the chassis or anything on the PSU. I was earth and wasn't part of the circuit so I was safe right?
Wrong. The capacitors somehow discharge into the magnet through me and boy did it hurt. I maintain that the magnet didn't actually touch the capacitors just hovered over them. Is it possible that the electromagnetic fields interacted with my poor hand through the magnet?
Till this day I will never forget that and I NEVER let magnets near capacitors again!
Its funny dealing with HV capacitors + magnets is my only phobia because I know I cant control or predict them.
Registered Member #350
Joined: Mon Mar 27 2006, 05:14PM
Location:
Posts: 106
If the plastic is thicker then the distance is larger and the field will be more stretched. Is that what you mean?
In the PSU there is an ac current flowing with a frequency of several tens of kHz. That could produce an electric field that induces a voltage in the magnet. But that has nothing to do with the magnetic field. It would also work with a piece of aluminum instead of the magnet. Also I don't believe that that was the reason you got the shock. There would be way too little current transfered through the field to feel a shock. So the only possiblility is that you touched it and didn't notice it. Maybe the magnet touched a wire that was coming from the circuit.
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On Capacitors and Capacitance
