13  EFFECT OF DIELECTRIC ON CAPACITANCE
With the understanding of the behaviour of dielectrics in an external
field developed in Section 2 10, let us see how the capacitance of a parallel
plate capacitor is modified when a dielectric is present As before, we
have two large plates, each of area A, separated by a distance d The
charge on the plates is ±Q, corresponding to the charge density ±s (with
s = Q/A)