Problem 3.86

Half the space between two concentric electrodes of a spherical capacitor is filled, as shown in Fig. \(3.14,\) with uniform isotropic dielectric with permittivity \(\varepsilon .\) The charge of the capacitor is \(q\) Find the magnitude of the electric field strength between the electrodes as a function of distance \(r\) from the curvature centre of the electrodes.