WAEC Physics 2021 Paper

Concept:Capacitance of a parallel plate capacitor is given by $C = \dfrac{\varepsilon A}{d}$, where $A$ is plate area, $d$ is separation, and $\varepsilon$ is permittivity of the dielectric.Explanation:Increasing the plate area $A$ raises $C$ because $C$ is directly proportional to $A$.Inserting a dielectric between the plates increases $\varepsilon$, which also raises $C$.Increasing the plate separation $d$ lowers $C$, while changing potential difference does not affect $C$.Thus, the actions that increase capacitance are increasing plate area and inserting a dielectric.Answer:A. I and III only