RE-NEET 2026 Physics Electric Potential MCQ Question

A unit positive point charge is taken slowly through an infinitesimally thin tube that is inside a charged dielectric tube that is inside a charged dielectric sphere of radius R, having uniform positive charge density ρ, as shown in the figure. The initial and final positions of the charge are marked by A and B at distances 2R and 3R respectively, from the centre of the sphere. In this process, the magnitude of the total work done on the point charge is $\frac{\rho R^2}{n \varepsilon_0}$. The value of n is ($\varepsilon_0$ is the permittivity of vacuum).