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Leyden Jar - 2 bottles - 1 positive 1 negative?

  1. Sep 30, 2011 #1
    I never could get leyden jars to work. I'm trying to use a few 3 liter bottles I have here at home. I also have quite a few solar panels and other materials like aluminum foil and copper.

    I was thinking today that it seems it would be easier to have 2 bottles, 1 with a copper lead dipping down into the water of the jar to use as a positive pole and another bottle with a copper lead dipping down into the water of the jar to use as a negative pole.

    Will this work?

    Can I charge the 2 bottles up with the positive and negative leads of my solar panel?

    Would the charge from a 3-6 volt solar panel be enough to get a spark over time if I touch the 2 leads from the 2 bottles together after a few minutes?

    Thanks.
     
  2. jcsd
  3. Oct 3, 2011 #2

    NascentOxygen

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    Water? Wherever did you get the idea they are filled with water? I think the chain just coils around a few times on the bottom of the empty jar, in the originals. Moisture is the last thing you would want around where you are trying to store static charge.

    You could try coating the inside and outside with separate metal foils to obtain higher C.

    6 volts from a solar cell with always be just 6 volts no matter how long you leave it connected. You won't get any sparks from charging from that.
     
  4. Oct 4, 2011 #3
    Other people keep filling it with water, salt, and/or bleach then just put the probe down into the liquid. I think they are just making a chemical battery and don't know because I had no problem lighting up an led with that solution and a metal probe connected to a copper probe.

    So I guess there is no way to charge up a leyden jar without a 10,000 volt source. I'll never have a 10,000 volt source so I guess there is no reason to ever make one.

    It's strange though that you say small volts won't spark, if I connect both ends of my car (12-volt) battery together they spark, even a 1.2 volt rechargeable battery sparks in the dark when I touch one end to the other.

    I could find no way to make tin foil stick well to the inside or outside of a jar or bottle either, no matter how much duct tape I used so I guess most of the leyden jars I see on the net are hoaxes.

    Also, I'm not going to walk around dragging my feet on my carpet all day trying force shock charge a non-working leyden jar either, that would just be even more ridiculous than forcing a coke can into a hydrogen peroxide bottle and coating it with tin foil, (no water or salt) which didn't work either...
     
  5. Oct 4, 2011 #4

    NascentOxygen

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    Other people? Who are these other people? Can you tell me their names? [Maggie Thatcher quote that springs to mind :smile: ]

    If you like experimenting, there is a way to get 100kV. It just uses metal cans, wire & stuff, and dripping water. I may post it sometime, but there's sure to be an online source. I've not tried it, but I recall seeing it in a science magazine. Maybe Sc Am. Quite ingenious.

    If those are the sparks you're after, then you've achieved your goal! I was speaking of sparks due to arcs. You can sure get big sparks by brushing stranded wire across your car battery terminals! (Don't try it.)

    It doesn't have to cling to the glass. Just stuff it in and push it up against the sides as best you can until it stays in place. Maybe double it over, and again, or buy the heavier gauge kitchen foil. No need for sticky tape.

    But I'm sure there are more interesting things to construct than a Leyden jar. :smile:
     
  6. Oct 5, 2011 #5

    NascentOxygen

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    It's Kelvin's electrostatic generator. Plenty about it online, including a video.
     
  7. Oct 5, 2011 #6

    sophiecentaur

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    Bad idea to use water in your jars - it would be all too easy to produce damp tracks which could short the two plates of the 'Condenser' (now there's a quaint old word) before a decent PD develops

    You need the inner and outer foils to be close together for a high capacity. Use sticky stuff to stick the tinfoil to the inside and outside. Leave a space below the top rim of the jar to avoid tracking over the rim. The Leyden Jars we had at School were all nicely painted with shellac, too.
     
  8. Oct 25, 2011 #7
    Thanks, sticky stuff, I looked for aluminum tape in construction stores but you can't find anything when you need it, it seems like I would see it everywhere before, now it has just disappeared, I quickly forgot about the tape then used aluminum flashing instead but I just googled "aluminum tape" and found some for $5 online, so I'll order some and give this one more go.

    I just don't think I can collect enough charge in my house to get a shock/spark to charge up the jar. I can't even get a shock off the door-nob which is weird since my house is carpet on top of a suspended wood floor. It's seems like I would be getting shocked everyday? I'll try a wool sheet rubbed repeatedly against my roll of aluminum flashing. Aluminum flashing collects a huge amount of static just sitting in storage, add wool and the result should be explosive.

    I also really like "Kelvin's water dropper," I already have a printout of his setup to do later, it is very simple. I'm really interested to see how many volts I can get out of it with my multi-meter. My ultimate goal is to hook up a spark plug and/or ignition coil to get it to spark when it reaches several thousand volts.

    And for those who said water won't work...

    Wikipedia:
    Water Electrical Conductivity
    Pure water containing no ions is an excellent insulator, but ... it almost always has some solute dissolved in it, most frequently a salt. If water has even a tiny amount of such an impurity, then it can conduct electricity readily... A salt or acid contaminant level exceeding even 100 parts per trillion (ppt) in otherwise ultra-pure water begins to noticeably lower its resistivity by up to several kΩ·m. The electrical conductivity of water increases significantly upon solvation of a small amount of ionic material, such as hydrogen chloride or any salt. Any electrical conductivity observable in water is the result of ions of mineral salts and carbon dioxide dissolved in it...

    I used a 50/50 solution of water/(salt/bleach); works great as a chemical battery using copper/iron leads in series across a few 3 liter bottles to light up a LED for a few days.
     
  9. Oct 25, 2011 #8

    vk6kro

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    It is necessary to make a reliable contact with the fragile Aluminum foil inner conductor. I have used steel wool to do this.

    You just make a ball of steel wool and put it inside the Leyden Jar so that it presses firmly against the Aluminum foil inside the Jar. Then plunge the centre conductor into the steel wool and it will make a reliable contact with the inside foil of the Leyden Jar.

    These are used on Wimshurst machines and withstand several thousand volts. Steel wool will rust if it gets wet, but lasts for many years if it is kept dry. The lid of the Jar keeps it dry enough.
     
  10. Oct 25, 2011 #9

    NascentOxygen

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    No, not at all. Only in low humidity should you expect a shock. For most of us, that means winter, especially cold clear evenings when the moisture has settled out as frost. When I push a trolley down the aisles of the supermarket during winter night shopping, I can draw sparks exceeding 0.25 inches off metal. I try to discharge my trolley against every unsuspecting trolley standing idle along the aisle, so that when I reach to take a can off the shelf my knuckles scream less with pain. Let me tell you, the novelty wears off at the second shock. :mad:

    No one here said water won't work (in a wet cell). What 2 of us said is that water has no place in or on a Leyden jar accumulator.

    Seeing your subject title reminds me, you don't have a positive jar and a negative jar. You only need one. It has both polarities: the foil inside is + and outside or environment is - (or the other way around, which ever you wish). If you construct a pair, then you would connect them in parallel.

    Your results from "rubbing the cat with nylon" type experiments will always be disappointing unless you can perform them in a low humidity environment; that time of the year when putting the key into the car door gives you a jolt. (So be doubly careful about discharging yourself to the car body before going near the petrol cap to refill your fuel tank. Remember: discharge BEFORE reaching for cap, and well away from it; and if you wander off or get back into the car, discharge again before venturing near the fuel.)
     
  11. Oct 25, 2011 #10
    I wouldn't recommend charging a Leyden jar with a 10,000V DC source since that is mega dangerous, but you can easily get thousands of volts safely with static electricity. A Van DeGraff generator will do, or just shuffling across a carpet on a dry day.
    That's for a totally different reason, and has to do with the inductance of the wires. I wouldn't recommend shorting out a car battery as a way of getting sparks, since there's a possibility of destroying it with the massive heat generated by the huge current. It might even explode.
     
  12. Oct 30, 2011 #11
    Building a leyden jar is actually very easy if you know how to do it.
    There are a few good videos on youtube. e.g.




    You can put water inside but it's better to use no water and cover the inside with aluminum foil instead. The jar/bottle should be made from plastic. Glas will work theoretically but causes too much trouble in practice. The foil and/or water should not go all the way to the rim of the jar. Covering the lower 2/3 of the jar is enough. The wire that leaves the jar should not have a sharp point at the top. Pointy metal objects tend to discharge through the air. A knob like in the first video is the best option. A bent wire or a nail should also work for small leyden jars. A few volts are not enough to get a spark out of it. You need a few thousand volts. The easiest way to do that is to use a PVC pipe and rub it wth a piece of cloth like the Mythbusters did in this episode

    Another simple option is to use an electrophorus


    But leyden jars are very simple capacitors. You can build more efficient ones by using 2 pieces of aluminum foil and 2 pieces of plastic foil. Put them together and then you can roll them up or fold them up like in this video

    The thinner the plastic foils are the higher the capacity but the lower the maximum voltage. The guy in the video probably only used very thin foil and charged the thing to a few hundred volts. A few 100 V can be produced very easily with a battery, a small transformer, a switch and a diode.
     
    Last edited by a moderator: Sep 25, 2014
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