# capacitance calculation

Discussion in 'General Electronics Chat' started by samjesse, Aug 14, 2009.

1. ### samjesse Thread Starter Senior Member

Sep 14, 2008
212
0
the formula to calculate the capacitance is

C = (ε A)/d

where ε is dielectric absolute permittivity
A is the overlap area in what units?
d is the distance between the plates in meters

what is the formula to use the relative permittivity instead?

Thank you

2. ### studiot AAC Fanatic!

Nov 9, 2007
5,003
523
area is measured in square metres in the MKS (ISO) system.

3. ### rspuzio Active Member

Jan 19, 2009
77
0
> A is the overlap area in what units?
> d is the distance between the plates in meters

Since you will measure d in meters, to be consistent, you
need to measure A in square meters.

> what is the formula to use the relative permittivity instead?

Write $\epsilon = \epsilon_{rel} \epsilon_0$, where
$\epsilon_{rel}$ is the relative permittivity (a.k.a.
dielectric constant) and $\epsilon_0$ is the vacuum
permittivity (which equals $8.85 \times 10^{-12} \, F/m$).

Last edited: Aug 14, 2009