Two different dielectrics fill the space between the plates of a parallel-plate capacitor as shown in Fig. $24-31 .$ Determine a formula for the capacitance in terms of $K_{1}, K_{2},$ the area $A,$ of the plates, and the separation $d_{1}=d_{2}=d / 2$ [Hint: Can you consider this capacitor as two capacitors in series or in parallel?]