# Can I be privileged by getting the answer on how to charge a leyden jar capacitor ?

I want it really fast as my exhibition stars 2 hrs from now.......................HELP!!!!!!!!!!!!!

sort by: active | newest | oldest
orksecurity7 years ago
Presumably, by now it's too late. When you're in a hurry, it's a LOT faster to do your own research than to ask others to answer the question for you -- or to ask someone who knows (eg a teacher) or someone who knows how to look things up efficiently (eg a librarian) for assistance.

Generally, you want to charge it from a high voltage/low-current source -- static electricity generator, usually. A few kilovolts at almost no amps. A van de Graff generator, or Wimhurst machine, would be classic solutions. Ask your school's physics teacher; there's probably something you can borrow for the purpose..

Be careful. Large leyden jars can accumulate enough charge to be dangerous. If you haven't had time to determine how yours behaves, don't assume it's harmless.
BANANI (author)  orksecurity7 years ago
The thing is..... the sparks produced are really very less, barely seen in the light...and as soon as the current is stopped from charging it, it gets spontaneously discharged and no amount of charge is stored in it....Besides how do I calculate the potential difference across the capacitor.PLASE HELP THIS POOR SOUL.
7 years ago

If it spontaneously discharges, then you've got a short somewhere. Either you've got metal from the lid contacting the inner foil, or a hole through the container or something.

Remember that a capacitor works by having two disconnected sheets of metal separated by a dielectric. If there is a current path connecting the metals, you don't have a capacitor any more.

The voltage is given by Q = CV, if you know the total charge stored (e.g., current supplied multiplied by time) and the capacitance (calculable in theory if you know the areas of the plates, their separation, and the dielectric constant), then you can get the voltage. More reasonably, you can use a voltmeter to measure the voltage once you're able to charge it up.

BANANI (author)  kelseymh7 years ago
And how do I raise the amount of sparks.....Furthermore I didn't have a cubical magnet to attach my sphere so I used up a magnet which was in the shape of a big tyre. I placed it all around the screw and placed the ball on top of the screw.Will it be equally efficient? And lastly.........plz don't be vexed...do I connect the positive terminal of voltmeter to the aluminium foil and negative to the sphere to get the reading????????????????????????????????????
7 years ago

You need to get your device to hold a charge before you do anything else. You need to find and eliminate the short. Once you've done that, you should be fine. But please be careful! If your Leyden jar works correctly, it can store enough total charge to kill you.

For measuring the voltage, it doesn't really matter which way you put the leads. If you have them the "wrong" way, the meter will read negative voltage.

Good luck!

BANANI (author)  kelseymh7 years ago
You are such a sweet-heart....Thank you so much.But there is one more question...How much charge can be stored in the jar?Can we demonstrate it by ligting some bulb or anything of that sort........and how much amount of salt must be dissolved per litre water..And you haven't answered how do we increase the amount of sparks and about the magnet.........
7 years ago
Calculate it, Capacitance = permittivity of free space x relative permittivity x Area of plates/ gap between them.

Energy stored = 1/2 x C x V^2. Unless V is very high energy store = very little, it doesn't take much to kill you though.

What do you mean by "increasing amount of sparks" ?

Steve
BANANI (author)  steveastrouk7 years ago
I mean there is barely any spark when I bring the metal ball in contact with a 220V circuit...But the aluminium foil does show a very high voltage..
7 years ago
You won't charge it with AC will you ?
BANANI (author)  steveastrouk7 years ago