# Variable separation capacitor

1. Mar 13, 2012

### Peytonator

Hi there,

I'm trying to calculate the average capacitance of a "variable separation capacitor." Google (and all my textbooks) are not helping me at all.

The capacitor has two parallel plates, one of which is hinged at one side. Sort of like this...

V

Basically I need an expression for the capacitance in terms of the displacement between the sides opposite to the hinge. Could you help me find an expression for this?

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EDIT: After looking the derivation for a normal cap, its obvious that the new capacitance is a function of x (distance from the hinge to other side):

C = εA/mx

where m is the gradient of the one plate with respect to the other. However, is there a way to get average capacitance?

Last edited: Mar 13, 2012