In the following circuit with an ideal operational amplifier, the capacitance of the parallel plate capacitor C is given by the expression C=(ϵA/x), where ϵ is the dielectric constant of the medium between the capacitor plates, and A is the cross-sectional area. In the above relation, X is the separation between the two parallel plates, given by x=x₀+kt, where t is time; x₀ and k are positive non-zero constants. If the input voltage v_i is constant, then the output voltage v₀ is given by