Leyden Jar Experiment

[arneish_prateek]

i need help in understanding "charge cycle" in the experiment "Where there is Charge, there can be sparks" under the section Charging The Leyden Jar of the project
i am confused about what it really means, and how to proceed

[deleted-71487]

The basic idea is that you're trying to get a repeatable amount of charge onto your Leyden jar for the various parts of the experiment.

In order to do this, you take one basic amount of charge, and you repeat it 1, 5, or 10 times. So you'd rub the acrylic for 30 seconds, and transfer the charge to the jar. That's one "charge cycle". If you then repeat this 5 times (rub for 30 seconds, transfer to jar, repeat) so that there's 5 times as much charge on the jar, that would be 5 charge cycles.

Does that make sense? Please let me know if you have any additional questions.

[arneish_prateek]

yeah..thanks, i got it
but i was wondering if the amount of charge that can be stored in the jar...is it endless? i mean, we can keeping running charge cycles, and every time some amount of charge is stored into the jar...so that means that the jar can hold endless amount of charges??

[deleted-71588]

is it endless? i mean, we can keeping running charge cycles, and every time some amount of charge is stored into the jar...so that means that the jar can hold endless amount of charges??

No. There always seem to be boundary conditions where the physics change.

A Leyden Jar in electrical components terminology is a capacitor. On of the boundary conditions for capacitors is the break down voltage.

If you look at the Neils Bohr model of an atom, in order for an atom to temporarily hold more electrons than its nominal number to match the number of protons it has, they have to be stacked in the outer orbitals. Once you fill an orbital, they have to take on additional energy and start filling the next orbital. This equates to some electro-motive-force or electron volts.

Because like charges repell, excess charge is a surface phenomenom. In order to get away from other electrons in a conductor (electrode), they migrate to the orbitals of the surface atoms. Because there are a finite number of surface atoms, there are a finite number of excess electrons that a capacitor's electrode can store at a given energy level.

When the voltage (electro motive force) needed to store more electrons exceeds the break down voltage of the dielectric (insulating material) or a leakage path, electrons will flow through the dielectric or around the dielectric. This can be a catestrophic event, explosive hole creation in the dielectric material or carbonizing (burning) a leakage path, or it can be a slow leak over time.

If you analyze your charge generation cycle, it probably has some physical limitations as well. There comes a point where the electron flow from the generator to the capacitor matches the leakage electron flow from the capacitor back to the charge generator. For charge generators that are safe for somebody of your age and experience to experiment with, the generator is is likely the limiting factor.