Question

State the effect on capacitance of a capacitor if (a) the thickness of the dielectric is doubled.
(B) the effective plate is halved

Answer 1

The capacitance of a parallel plate capacitor is given by

$C=\frac{\varepsilon A}{d}$

where $C$ is the capacitance,

$\varepsilon$ is the permittivity of the dielectric material,

$A$  is the area of the plates and

$d$ is the separation of the plates.

Here $d$ is also the thickness of the dielectric material between the plates.

(a) Since $C\propto \frac{1}{d}$ , if the thickness of the dielectric is doubled, the capacitance becomes half.

(b) Since $C\propto A$ , if the effective plate is halved, the capacitance becomes half.