Two capacitors C1 and C2 are connected in series to a 12 V
battery as shown in the sketch. Each has a dielectric filling
the volume between the plates, with K1 = 4.0 and K2 = 2.0.
Without a dielectric between the plates the capacitors C1 and
C2 each have capacitance C0 = 2.0 X 10-6 F. What is the
voltage across C1?