(II) Two different dielectrics fill the space between the plates
of a parallel-plate capacitor as shown in Fig. $31 .$ 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?]