» Chemistry and experiments »Liquid rheostat (experiment)

Liquid rheostat (experiment)



Hi everyone, I am starting to conduct a series of experiments that I have long wanted to do. Specifically, this article will be devoted to the experiment with a liquid conductor and the creation of a rheostat based on it. Such a rheostat can control a variety of capacities, from a few watts to several hundred or even thousands of kilowatts, however, in the latter case, the dimensions of the rheostat will be very rather large. But in general, I am not interested in a rheostat, I am interested in the properties of liquid conductors, in my case it is ordinary water with a conductor in the form of kitchen salt. So, let's get down to business.

Materials and tools that were needed:

Material List:
- table salt and water;
- wire (I have copper);
- boards;
- a bolt, a nut (and another piece of something for the handle);
- self-tapping screws;
- Super glue;
- a piece of soft tube;
- wires, power supply, LED or other load.

Tool List:
- a hacksaw;
- ;
- screwdriver;
- ;
- .

Manufacturing process:

Step one. The foundation
He riveted the base for an ambulance from the boards, everything can be glued with superglue or twisted with screws. You can make a base from other materials, for example, from wire.


Step Two Valve
By clamping the tube, we reduce the cross section of the liquid conductor, as a result, less current passes through it. Of course, it is more convenient to use a faucet here, but it should be made of plastic or other material that does not conduct current. However, my design works well, and most importantly, clearly.





The clamp was made of two bars, glued a nut in the upper one, and sharpened the bolt that was twisted into it at the end. A stud was welded to the head of the bolt as a handle. At first I wanted to make the pressing part of wood, but everything worked tightly, as a result I took a coin, it has a recess in which the end of the bolt enters. Here are such mini-vices. I screwed the pieces of the bars with screws.

Step Three A tube
We install the tube, I attached it with wire brackets. We install electrodes in the tube on both sides, in my case it is a copper wire. Of course, copper from salt and electrolysis quickly collapses, but did not want to mess with stainless steel, and for the sake of the experiment, there will be enough copper.





The ends of the electrodes are inserted into the holes in the board and glued, sit tight. In the end, you can pour and electrolyte, in my case it is water with a high salt content. I added ink from the printer as a dye. That's all, now solder the wires, looking for a power source and load.

Step Four The experiments


1. As an experiment, I connected a 12V / 4W lamp, I did not pull the rheostat, and electrolysis started. The point is the small area of ​​the electrodes, it is not designed for such power and more than it can, the rheostat will not allow current.

2. I connected the LED from the flashlight, I do not know how much Volt and Watt it is, but the 9V crown does not glow at all its power. The rheostat controls the LED perfectly, there is no electrolysis, or maybe it is too weak, and I do not see it. It is not so easy to completely turn off the LED with a rheostat, you need to tighten the tube very much to displace all the water from it.

3. I connected the motor from the drive together with the LED, the rheostat controls perfectly the revolutions, and the brightness of the LED has become much easier to adjust, the adjustment range has become smaller. The fact is that the motor is able to operate at a lower voltage than the LED. While the motor reduces speed, the LED is already off.
As for electrolysis, with such a load it proceeds, but not very actively.

conclusions
The rheostat is viable, its power depends on the area of ​​the electrodes, and the operating voltage depends on the length of the tube (liquid conductor). The farther the electrodes are from each other, the less conductivity between them and the greater the voltage required.

Of course, the lack of a rheostat is in the evolution of gas and heating of the liquid, but, as I said, the idea is not to create a rheostat at all. At the moment, I am interested in what will happen with a large current on the thinnest section of a liquid conductor. So, the wire simply burns out, and water can decompose into hydrogen and oxygen. Of course, experience has not yet confirmed this, and it will not confirm it, probably, because with a decrease in the cross section the current strength decreases, which is necessary for the splitting of water into oxygen and hydrogen. But in this case, you can try to increase the voltage ...
If you have ideas what else to check with such a rheostat, write, we will conduct an experiment!
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18 comments
Author
And how can it happen, explain? A closed container that can withstand tremendous pressure, two electrodes inside ... At first, electrolysis can and will be until the pressure rises. And then what? Explosive gas will burn inside and turn into chtol again?))
In any case, the water will remain inside unchanged. Or not?)
Quote: Dmitrij
No electrolysis under pressure
This is a new word in science.)) The fact that you do not visually see gas evolution does not mean that there is no electrolysis.
Author
There is no electrolysis under pressure, as is boiling. But this is a completely different story and my other homemade :)
Taras
There can be no electrolysis, you do not have mercury and not gallium. And in order to miss millions of watts and not to boil, it must be large, which will affect the resistance, as a result, large power will be lost even at the maximum cross section. In addition, not only the overall dimensions are important, but also the dimensions of the narrowest part. Accordingly, the minimum cross-section will be limited, or it is necessary to change the design.
Ha, self-preserving circuit, that’s something ...
Author
The electrolyte boils, the electrodes are heated by electrolysis. It can be made in a plastic or metal bucket, then I think it will not boil over a night from 5A.And if it boils, let it boil, the maximum water will boil and the cell itself will interrupt the circuit.
2 Ivan_Pokhmelev
... Any load will be heated, and the same, regardless of its type ....
Goat understand ...
... Liquid loading is no better ...
I didn’t come across this, although if I hung plywood with all the bells and whistles on the wall, maybe there would have been nothing.
... The electronic load is called. ;) ...
I tried two options - field workers as keys with a nichrome resistor, and field workers as active resistors, controlled from the outside, from the control board. The second is better, but it just doesn’t need anyone.
One to one - the end is 2 to 600 watts, what the hell is the electronic equivalent, 1.2 mm nichrome, a 4 liter pan boils for 5 minutes. And the jar - well, it's hot and easy to drop. Enamel pan with handles.
And how I did powerful loads. I took PEVs, ceramic resistors, nichrome spirals, which turned up by the arm (of course, I didn’t need the required resistance), let the wires down and put them into a 3 liter jar of water! yahoo
Quote: ino53
light bulbs in the role of load are not very good - they warm up, burn out, beat,
Any load will be heated, and the same, regardless of its type.
The liquid load is no better - it is unstable, pours out, evaporates, and undergoes electrolysis.
If you do not like bulbs - a set of sewers + a powerful transistor on a radiator with a strapping that stabilizes the current. The electronic load is called. ;)
Interesting, it will be necessary to search. But I mean a little different - a repaired or freshly made memory is put on run for 4-6-8 hours, the light bulbs as a load are not very good - they heat up, burn out, beat, you can not find a healthy school rheostat now. Maybe bring this design ...
instead of kitchen salt, you need baking soda
cerebrospinal fluid, blood plasma has relatively good electrical conductivity and, excuse me, urine! xaxa
Author
Yes, I know, graphite shore for other experiments)
Author
I charged from an inverter welder through a battery electrolyzer, somewhere in the discussions there was a topic
I wonder if the current can be adjusted within 5 ... 10 A at 14 V, i.e. 1.5 ... 3 Ohm (test car charger-tv)
Instead of copper conductors, it is necessary to use graphite, they can be taken from old batteries, because copper is quickly oxidized, and instead of kitchen salt, baking soda is necessary (it releases hydrogen), otherwise chlorine will come out, and it will be toxic, gas must be removed, because it will be even more increase resistance dissolving in liquid
Author
blood is suitable, also conducts excellent current)))
The liquid in the tube is like pig blood-))))

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