A parallel-plate capacitor has a capacitance of C when the plates are separated by a distance d. If the separation is doubled while the area of the plates remains constant, the new capacitance will be:

Core Concept

The capacitance of a parallel-plate capacitor is given by C = ε₀A/d, where A is the area of the plates and d is the separation distance. If the separation distance is doubled (2d), the new capacitance becomes C' = ε₀A/(2d) = C/2. Thus, the capacitance is halved when the plate separation is doubled.