C = ε0A/(d1/εe1 + d2/εr2) = (8.854 x 10-12 x (0.5)2)/((6 x 10-3/2) + (4 x 10-3/1)) = 3.16 x 10-10F
= CV = 3.16 × 10−10 × 100 = 31.6 × 10−9 C
D = Q/A = 31.6 × 10−9/(0.5)2 = 1.265 × 10−7 C/m2
The charge or flux density will be the same in both media i.e. Da = Dt = D
In air, E0 = D/ε0 = 1.265 × 10−7/8.854 × 10−12 = 14,280 V/m
In Teflon, Et = D/ε0εr = 14,280/2 = 7,140V/m
Vt = Et × dt = 7,140 × 6 × 10−3 = 42.8 V