
A thin spherical insulating shell of radius carries a uniformly distributed charge such that the potential at its surface is . A hole with a small area is made on the shell without affecting the rest of the shell. Which one of the following statements is correct?


Important Questions on Electrostatics

is the permittivity of free space]





A parallel plate capacitor has a dielectric slab of dielectric constant K between its plates that covers 1/3 of the area of its plates, as shown in the figure. The total capacitance of the capacitor is C while that of the portion with dielectric in between is . When the capacitor is charged, the plate area covered by the dielectric gets charge and the rest of the area gets charge . The electric field in the dielectric is and that in the other portion is . Choose the correct option/options, ignoring edge effects.




Two non-conducting solid spheres of radii and , having uniform volume charge densities and , respectively, touch each other. The net electric field at a distance from the centre of the smaller sphere, along the line joining the centres of the spheres, is zero. The ratio can be
