Class 12 | Electric charge and field | An infinitely long solid cylinder of radius R has a uniform volume charge density. It has a spherical cavity of radius R/2 with its centre on the axis of the cylinder, as shown in the figure. The magnitude of the electric field at the point P, which is at a distance of 2R from the axis of the cylinder, is given by the expression 23ρR/16kɛ0. The value of k is