RE-NEET Physics Electrostatic Potential And Capacitance Class 12 Questions

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).

A point charge Q is placed inside a cavity within a solid isolated conducting sphere. Consider points A, B and C as shown in the figure, where the magnitudes of the electric fields are Eₐ, E_b and E_c respectively. The points B and C are at the same distance from the center of the solid sphere. The correct option is:

Three identical capacitors P, Q and S, each of the capacitance C, are connected to a battery of voltage V, as shown in the figure. If the energy stored in the capacitor P and total energy stored in the system are Uₚ and Uₜ, respectively, then the ratio Uₚ/Uₜ is: