Electricity and Common Urban Myths

[JorgensenSteam]

Yes, I agree, you could discuss it forever, and never really know exactly how it works, but what is really important is how does it effect things, and luckily this can be easily measured.

Pat J

 

[Noitoen]

All I know is that, if you leave your Ether bottle uncapped, it will evaporate :big: :hDe:

 

[mu38&Bg#]

I got to watch a rather large Telsa coil last summer. The demonstration was impressive. It was built by a few EE's just out of college.

 

[Don1966]

Heh guys! I got a good question for you when you charge a capacitor were does the charge go?

Don

 

[JorgensenSteam]

Wow, that photo brings to mind what my mother seemed to constantly ask me, which was "Is it safe to be doing that?".

My stock answer was always "Of course it is safe to be doing this, I would not be doing it if it were not safe", which translated meant "it is not safe, but I am too dumb to know the difference".

As I recall (it all gets a little hazy now, so don't slam me if I get it wrong) inductors store energy in the magnetic field and capacitors store energy in the electric field.

Lots of people have been zapped by the old TV's that did not have an automatic method to discharge the capacitors when the set was unplugged from the wall.

Pat J

 

[Don1966]

Partial correct but where is the Electric Field?

Don

 

[Noitoen]

Two plates, separated by a dielectric, one "robbed" of the electrons and left with holes and the other with the exact amount of excess electrons to fill the holes.

 

[mu38&Bg#]

Yes, the guy in that photo is safe. He's wearing a chain link metal suit with a wire cage over his head. That doesn't mean he wasn't nervous trying to touch the arc.

 

[Don1966]

Yes that is awesome photo dieselpilot I have seen many if these guys go so far as to build these towers in there back yard and make it shoot into the sky. And these were not small towers bt huge.

Noiteon that is not correct given a hint you can take the two plates and seperate them from the dialect and touch them together and nothing will happen. So where is the electric field?

Don

 

[Noitoen]

I would think that if you separate the plates after they are charged, they would keep the charge much like a a comb charged with static or doesn't it?

 

[purpleknif]

Ya know, you guys are gettin into some heavy physics here. When I watch those shows on the Discovery Channel and there's something I don't quite get I ask my wife about some of the math and such. She has a PhD in abstract mathematics. Her answer is always the same. "That's physics. Physicists are all wackos."

 

[Don1966]

I would not call it heavy physics but basic Electronics.

Back to you Noitoen the plates were touched together would that not discharge them even by touching them?
It might be hard to believe, but the charge exist on the outer surface of the dialectic. The way to prove this is to charge a capacitor you can take apart charge it with high voltage and take it apart. But be careful when you do, use a insulator to seperate the plates when you remove it from the dialectic. Short them together and place it back together then discharge it.

Regards Don

 

[Stan]

That is interesting. If the charge is on the dielectric, do capacitors with air as the dielectric work the same way?

 

[Herbiev]

Don. IIRC c=ak/d. C is capacitance, a=area of plates, k= dielectric constant and d= distance between plates. If we use air as the dielectric ( as in the old tuning capacitors) would not the charge dissipate when the plates are removed as both "a" and "d" have been drastically altered or am I missing the point. It's been 50 years since I did my electronics course in the telecommunications field. In those days we called them condensers and were told that a 1 farad condenser would be the size of a city building. Boy times have changed. ;D

 

[Don1966]

I had done some test with air as a dielectric, as long as the plates are close together the charge remains. But once you move them apart the put them back close together the charge is gone. The charge will reside on the outer surface of the plates, but not on the plates. That is the only explaination i an give you about air. And when you turn a capacitor like a radio the charge should still be there and changes as per surface area and dielectric area. Don't get me wrong here this is not something I came up with, but fact. Try the test I had mentioned.
After posting this I did some searching and there seems to be some misconception between low voltage and high voltage capacitors so please read http://amasci.com/emotor/cap1.html

Regards Don

 

[Don1966]

If this guy is correct I also have been mislead this is not what I want. Thank you Stan and Herbiev for your questions. I had been taught that the charge moved form one plate to the next and resided in the plates, but through the years of reading researches had changed my mind this guy makes sense. I had done the test myself with high voltage and the Corna effect makes sense. I don't want to mislead anyone so please read the link below.

Regards Don

 

[kf2qd]

THe problem with the capacitor explanations is that the charge level is relatively low, and in the case of a tuning capacitor, it is operating under AC and not DC. You would have to separate the plates extremely quickly to be able to "store" the charge.

A charge can "stick" to a plate - I remeber the cat pelt and a plastic surface. Rub the fur and charge the surface and then the had an aluminum disk attached to an insulated handle - slap the disk on the plastic surface and then transfer the charge to some device that would indicate the charge.

Or - rub a ballon against your head - won't work for the bald guys - and ten "hang" the balloon on the wall.

If you make a large enough capacitor - 100's or 1000's of Farads, not micro or Pico Farads. charge it, and then unpeel it and you would find both both plates would have a charge - one low on electrons - the positive plate , and one with extra electrons a negative charge -

 

[Foozer]

Other ting that always queried my mind is the speed of the electron.
Rumor is "Speed of Light" The light photons from the sun move slow from the internal to the surface where they transition to the speed of light. HUH?
How? What changes to change its speed, as its speed increases something must diminish to keep equality. Time itself as the variable?

Same with the electron, (conductor) its sitting doing its attraction repulsion dance on the nucleus and soon as a mag field is walked by the electron does the SOL fly to the next atom in line. Its not dancing at the SOL, Perhaps I just better stick to shinny things and be happy.

Robert

 

[Herbiev]

Don. You mention that " The charge will reside on the outer surface of the plates, but not on the plates." It is interesting to note that in the early days the charge was thought to collect on the plates due to condensation, hence the name "condenser".
What I find more interesting is how this c#%p stayed in my mind for nearly 50 years when I only needed it for a couple of days just to pass an exam. Ask me what I had for dinner yesterday, and I'm stumped ???

 

[steamer]

Other ting that always queried my mind is the speed of the electron.
Rumor is "Speed of Light" The light photons from the sun move slow from the internal to the surface where they transition to the speed of light. HUH?
How? What changes to change its speed, as its speed increases something must diminish to keep equality. Time itself as the variable?

Same with the electron, (conductor) its sitting doing its attraction repulsion dance on the nucleus and soon as a mag field is walked by the electron does the SOL fly to the next atom in line. Its not dancing at the SOL, Perhaps I just better stick to shinny things and be happy.

Robert

I've stuck with the shiny bits and it works just fine for me! :big: