X 3 ει 82 Variable dielectric ε ε ε εε242 C= + d d Equivalent to C1 // C2 = →CT C1+ C2 Since A₁ = wx, A₁ = w(1-x), when w is the width of the plates, d = 1 mm EoW C = - [ε₂l — (ε₂ — ε₁)x] - w = 50 mm d 1 = 50 mm E=854x10-12 (F/m)