# The Naked Scientists Forum

### Author Topic: Can you charge a Leiden Jar using a plasma ball?  (Read 4146 times)

#### Theodidactus

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##### Can you charge a Leiden Jar using a plasma ball?
« on: 24/10/2010 16:46:49 »
hello guys!
This is my first post so I apologize if this is in the wrong place.

I was a keen experimenter as a kid (electromagnetism especially) but found that I wasn't good enough at math to hack it as a big time physicist. So I majored in the history of science, and took a job in Taiwan teaching children science, history, and literature. In my spare time, I tinker with the laws of the universe, and occasionally turn up fun stuff to show my kids.

Over the last month, I've been tinkering with Leyden jars, but I can't seem to get mine to work. Now, I love problem solving, but there are some problems here that I can't fix...I want to know if I've hit a dead end before I further my experiments.

My Leiden jar is a simple affair: a glass apple juice bottle filled with salt water, with a metal rod through the top. The outside of the jar is surrounded by aluminum foil and electrical tape, with a ground wire running out. I've used my electric toolkit to determine that there is no electrical connection between the metal rod (on the inside of the jar) and the aluminum foil (on the outside).

I know that the jar is working properly, by which I mean, I know that if I run a negative charge through the top of the jar, the ground wire on the outside will throw sparks when connected to ground (or my finger). I'm running the charge into the jar top by means of a fist-sized plasma globe (my most treasured possession). The problem is that I cannot get the jar to hold any appreciable charge, nothing that will create a visible spark. Here are my questions:

#1: Can you charge a leyden jar by linking it to a plasma globe? A wire taped to a plasma globe will throw sparks, and has a powerful negative charge, but every time I connect the wire to the top of the leiden jar, the thing stores no charge. Is there something fundamental I'm missing here?

#2: Is my alternative method for charging the jar going to work? Basically, I run a balloon repeatedly along a sheet of glass and then hold it close to the jar. By textbook examples, this seems to work, but am I doing this right?

#3: Is my problem that I'm located in Taiwan? The air here isn't exactly dry, but I can't imagine that it'd be so moist as to totally ruin my jar. If this is the case, what can I do to make the jar work right?

#4: Are there any other tips you can offer for leyden jar enthusiasts?

William

« Last Edit: 25/10/2010 18:34:33 by chris »

#### Geezer

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##### Re: Can you charge a Leiden Jar using a plasma ball?
« Reply #1 on: 24/10/2010 18:24:56 »
Hi Theo! Welcome to TNS (nice post BTW)

re #1, I don't think a plasma ball will reliably produce an electric charge. The plasma is created by an alternating RF field, so there (should be) no net charge produced.

You need a positive or negative charge only, so the baloon trick is likely to be more effective.

re #4 - Be very careful! If you are successful, you might be able to load quite a lot of high voltage charge into your jar. It could give you a very unpleasant electric shock. Actually, it might even charge up all on its own. You should keep it shorted when not in use.

Take a good look at this. Page 8 in particular.

http://euverc.colostate.edu/safetytests/High_Voltage_Safety_Manual.pdf

#### Theodidactus

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##### Re: Can you charge a Leiden Jar using a plasma ball?
« Reply #2 on: 24/10/2010 18:31:23 »
Thank you for reminding me about the warning.
I've made leyden jars before, but it is good to repeat the warning, especially for anyone who is trying this for the first time

DO NOT MESS AROUND WITH THESE

...though I must admit, part of the attraction of the jars, for me, is that they're so powerful but so simple.
Unless you have a good idea what you're doing, I wouldn't make one larger than a human hand. When I get more experienced making reliable models, I want to make a steampunk-looking one out of some gold leaf, cheap wine, and a brandy snifter.

...now if I could just get this jar to charge.

#### syhprum

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##### Can you charge a Leiden Jar using a plasma ball?
« Reply #3 on: 25/10/2010 22:36:36 »
A good source of high voltage to charge up your Leyden jar (1/900 micro Farad according to Earl Mountbatten) would be the EHT on a CRT type colour TV (about 28 KV) I need hardly add that great care should be taken setting up this experiment as the system will pack quite a nasty Kick !!!
« Last Edit: 25/10/2010 22:40:06 by syhprum »

#### Geezer

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##### Can you charge a Leiden Jar using a plasma ball?
« Reply #4 on: 26/10/2010 00:09:18 »
A good source of high voltage to charge up your Leyden jar (1/900 micro Farad according to Earl Mountbatten) would be the EHT on a CRT type colour TV (about 28 KV) I need hardly add that great care should be taken setting up this experiment as the system will pack quite a nasty Kick !!!

I suppose if Theo takes the bleed resistor off a CRT tube, he could use it as highly effective Leiden Jar  .

#### The Naked Scientists Forum

##### Can you charge a Leiden Jar using a plasma ball?
« Reply #4 on: 26/10/2010 00:09:18 »