Twelve capacitors with a capacitance equal to C are used to build the edges of a cube, as shown in the figure. Determine the equivalent capacitance between points A and G that is the diagonal of the cube.

A capacitor is formed by two plates of area A and distance 2d, between these plates are placed two insulators of dielectric constants k₁ and k₂ and thickness d, as shown in the figure. Determine the capacitance of this new capacitor. Given the vacuum permittivity ε₀.

Find the equivalent capacitance between points A and B of the circuit represented in the figure.