Example: Parallel Plate Capacitor
The capacitance depends on K, A, k and d:
Cparallel plate = K A / (4 p k d)
where K = 1 for vacuum, A = 5 cm x 5 cm = 25 cm2 = 25 x 10-4 m2, d = 2 mm = 2 x 10-3 m, and k = 9 x 109 Nt-m2/Coul2 , so C =
(1) * (25 x 10-4 m2) / [4 * 3.14 * 9 x 109 Nt-m2/Coul2 * 2 x 10-3 m] = 1.10 x 10-11 F = 11 pF .