10-20KV from running water, can you explain this?

[ThermalRunaway]

Hi everyone,

I "stumbled" across this **broken link removed** of an experiment involving running water, some conductive cans and a 20KV spark. In it, the lecturer asks his students to explain what is happening, but it's got me!

Can you explain it?

 

[Nigel Goodwin]

I would imagine it's static electricity?, the water running through the top can down to the opposite connected bottom can is transferring charge from one plate of a capacitor to the other plate - until it's high enough to jump over the spark gap.

However, I consider he's wrong calling it a 'battery', as it's taking moving water to create electricity, so it's more of a generator - converting mechanical energy into electrical energy (with probably VERY poor efficiency?).

 

[Andy1845c]

Can you explain it?

No..... I can't Very interesting though. Dosn't appear to be a hoax...... I am interested in knowing more about it.

 

[Pommie]

This must be a hoax. The reason I say so is that in order to get a spark there must be a potential difference. One bucket must be positively charged and the other negative. As both buckets are identical, how do the electrons know which bucket to accumulate in?

Mike.

 

[ThermalRunaway]

It is indeed strange, but I'm not buying the suggestion that it's a hoax just yet. I do wonder how the running water results in a potential difference of that magnitude and I can't answer why that happens, but I have a feeling it's real - it would be a pretty strange thing to hoax about!

Any further suggestions?

Brian

 

[Pommie]

it would be a pretty strange thing to hoax about!

I think this is a Uni demonstration not to believe everything you see. Especially on the Internet.

Mike.

 

[Souper man]

I think it could have somthing with different metal paintcans and buckets perhaps? maybe zinc and copper, but im just guessin

 

[audioguru]

I think electrons are stripped by the metal cylinders at the top. The polarity is random for each spark unless one side has more water running then its electrons are stripped more.

 

[Sceadwian]

I'm surprised no one's noticed yet. When the instructor goes up with the microphone you can see that the water flow into both containers isn't the same, more water is going into the B container, and that's the one that displays the static 'scattering' effect just before the spark.

I'm going to throw a theory out that when the water droplets seperate from the upper tank they pick up some charge from friction as they fall and since the water flows aren't equal there's a charge surplus in the one container. The buckets are obviously very well issolated from a ground source so the charge builds up untill it sparks from one bucket to the other.

Anyone else?

 

[Marks256]

This video was made at MIT (Massichussets Institute of Technology)

 

[Pommie]

Despite my earlier skepticism, I now think I know the mechanism by which it works. If 1 bucket gets a small charge, let's say the right bucket gains electrons, the cross connection means that the left upper cylinder also gets an excess of electrons which in turn "pushes" (repels) electrons away from the left stream and toward the right stream. The net effect of this is to amplify any potential difference through positive feedback. I would guess that for optimum results you would want a constant stream down to the upper cylinders and then droplets after.

Mike.

 

[kchriste]

Pommie's explanation seems to make the most sense to me.... The other thing I thought of is if bucket B (Upper right referring to the diagram in vid) gets a negative charge, it stands to reason that the water falling through and into bucket C will be positively charged. B is connected to D so the potential difference between D&C will build rapidly. It would be interesting to see if the polarity of the charge between D&C would change if different water flow rates existed on the right and left sides. Now who will be the first to replicate this experiment?

 

[Leftyretro]

Cool, but can I power my PIC from it ?

 

[Pommie]

Cool, but can I power my PIC from it ?

Yes, but not for long.

Mike.

 

[Nigel Goodwin]

Like I said at the beginning, it's just a static electricity effect - the displacement of the water helps to demonstrate that. If you charge an amber rod up and then hold it near a running tap the water is displaced.

But like all static electricity effects, it's far too low a current to be of any use (except for destroying CMOS devices!).

 

[JimB]

I am with Pommie for the basic explanation of how this works.

The water falling through the air is charged due to the "triboelectric effect", friction on the surface of the water stream.

The upper cans help to induce a charge on to the water stream flowing through them.

Where does the "energy" come from? Th water is falling, and so converting potential energy (height) into kinetic energy (motion) and a little bit of electrical energy.

If someone has a spare couple of hours, it should not be too difficut to reproduce this demonstration.

JimB

 

[Styx]

I am with Pommie for the basic explanation of how this works.

The water falling through the air is charged due to the "triboelectric effect", friction on the surface of the water stream.

The upper cans help to induce a charge on to the water stream flowing through them.

Where does the "energy" come from? Th water is falling, and so converting potential energy (height) into kinetic energy (motion) and a little bit of electrical energy.

If someone has a spare couple of hours, it should not be too difficut to reproduce this demonstration but using a bigger tank, bigger cans, bigger gap to produce a BIGGER potential.

JimB

just a quick correction if it gets done, it sgot to be bigger

 

[Sceadwian]

10-15kv isn't big enough for you? Depends on the charge size that spark released. The trick would be to turn that spark into a useable amount of lower voltage, maybe through a transformer charging a capacitor. Like a step down flyback transformer.

 

[Andy1845c]

Seems so simple to make I am surprised I haven't seen it before anywhere.

 

[Sceadwian]

Levitating a piece of graphite over strong magnets is pretty simple, not many people even know it's possible.