WAEC Physics 2011 Paper

Concept:The capacitance of a parallel-plate capacitor depends on the area of the plates, their separation, and the material between them.Explanation:For a parallel-plate capacitor, capacitance is given by $C = \frac{\varepsilon A}{d}$.Here, $\varepsilon$ is the permittivity of the medium between the plates, $A$ is the plate area, and $d$ is the plate separation.Inserting a dielectric material increases $\varepsilon$ by a factor $k$, the dielectric constant.The new capacitance becomes $C = \frac{k\varepsilon_0 A}{d}$, which is larger than without the dielectric.Capacitance does not depend on the potential difference across the plates.Also, decreasing the separation $d$ would increase capacitance, not decrease it.Therefore, the correct statement is that capacitance is greater with a dielectric between the plates than without one.Answer:D. is greater with a dielectric between the plates than without a dielectric.