# Electrostatic field

Discussion in 'Electronic Design' started by [email protected], Dec 26, 2006.

1. ### Guest

Hi,
As you know there is an electrical field around each electrostatic
charge. I know how to create an electrostatic field. But I have problem
by creating a "variable electrostatic field". Can you give me a guide?

2. ### Dirk Bruere at NeoPaxGuest

Vary the voltage of what's generating the field

Dirk

3. ### Guy MaconGuest

Use AC (alternating current) if you want a varying electmagnetic field.

Use DC (direct current) if don't want it to vary.

4. ### Tom BruhnsGuest

"Variable" and "static" are mutually exclusive, or a bit more
accurately, "varying" and "static" are mutually exclusive. You can
change an electrostatic field by changing the distribution of charges
which creates the field, and also by changing the dielectric (e.g., by
replacing some portion of the dielectric with a dielectric with a
different permittivity) which contains the field, but when the field is
changing, it is no longer static.

Consider, if you will, two flat metal plates, parellel to one another,
and separated by a short distance, with air (or a vacuum) between the
plates. Remove charge from one plate and put it on the other. You now
have a charged capacitor, with an electrostatic field which is most
intense, and reasonably uniform, between the plates. Now pull the
plates further apart, or allow them to come closer together. By moving
the charged plates, you will change the field between the plates (and
the field in the surrounding area). The charges will also redistribute
themselves on the plates at the same time. But the motion of the
plates and the charges on the plates represent currents, which create
magnetic fields, so during the time that the charges are moving, the
fields are not only electric, but magnetic as well.

Cheers,
Tom