Two square plates of side ‘a’ are arranged as shown in the figure. The minimum separation between plates is ‘d’ and one of the plate is inclined at small angle α  with plane parallel to another plate. The capacitance of capacitor is (given α is very small)

For small strip of width dx  and separation d+αx , differential capacitance can be given asdC=∈0adxd+αx All such strips are in parallel, so we will integrate the equation C.=∈0aαInd+αx0a =∈0aαIn1+αad  Use, In1+x ≃ x - x22 (for small values of x) ≈∈0aααad-α2a22d2 ≈∈0a2d1−αa2d