JEE Advanced Model Paper 1 with solutions for online practice

Consider a conducting sphere A having charge Q and radius a, placed concentrically inside a conducting shell B having radius b( > a) and earthed. Let C is the common centre of the sphere A and the shell B. If E and V be the respective electrostatic fieldand potential at a distance r ( a ≤ r ≤ b) from C and Δ V be the electrostatic potential difference between the sphere and shell, then