# Question about high electric charge.

#### Low-Q

Gold Member
Hi,

If I have two sheets which is highly electric charged, and with the same polarity of 100kV with respect to ground.
The sheets are 10cm^2, aligned in parallell surface to surface, and 1cm apart.
Now there is a repulsion force between them.

Let me say there is a transformer which is charging these sheets. The transformer transform 240V AC up to 100kV DC (rectified).

If I now take those sheets and change the distance between them periodically. How will this change affect the current that flows through the transformers primary winding?

What happens to the transformer if one of the sheets approach ground which it is electrically attracted to?

Vidar

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#### Simon Bridge

Homework Helper
The PSU is maintaining the PD between the sheets and the ground?
Why would there be a current flowing through the transformer to do that?

The changing force affects whatever is holding the sheets in position.

#### Low-Q

Gold Member
OK. Thanks. I assume then if one of the sheets is discharged to ground, it would affect the PSU, but not as the charge is constant.

What if the ground is also a sheet, but with positive charge. If that sheet comes in between the two other negatively charged sheets, what will happen with the force between the two negatively charged sheets?
Will it remain the same but partially counterforced by the positively charged sheet?

Vidar

#### Simon Bridge

Homework Helper
If you attached one of the sheets to ground the PSU that supplies it would overload yes... it's a short-circuit.

I suppose two positive plates close to each other would need more effort to keep the charges there - is that what you were thinking? But if the charges aren't moving, there's no current.

You can do all this without the PSU you know - just charge the sheets and don't let them discharge.

If the ground were also a sheet as described that you have two parralell-plate capacitors with a PSU maintaining the voltage between their plates. The net force experienced by each of the original (negative) sheets would be reduced though the force due to one sheet by the other one would remain the same.

You can also have fun with a parallel sheet capacitor using a PSU to maintain a constant voltage between them - then move the plates around and watch what happens on a galvinometer.

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