Derive an expression for the capacitance of a parallel plate capacitor of plate area \(A\) and plate separation \(d\) with air present between the plates.
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For a parallel plate capacitor:
\[
C=\frac{\varepsilon_0A}{d}
\]
Remember:
\[
C \propto A
\]
and
\[
C \propto \frac{1}{d}
\]
Thus, increasing plate area increases capacitance, whereas increasing plate separation decreases capacitance.