A copper plate of thickness b is placed inside a parallel plate capacitor of plate distance d and area A as shown in figure. The capacitance of capacitor is

In a parallel plate capacitor, the capacitance

For a parallel plate capacitor of capacitance C and plate separation d,

A sheet of aluminium foil of negligible thickness is placed between the plates of a capacitor of capacitance C as shown in the figure then capacitance of capacitor becomes

Two plates of parallel plate capacitor are joined inside with metal rod. The capacitance of a capacitor is ........... .