Two mercury drops of radii $ r $ and $ 2r $ merge to form a bigger drop. The surface energy released in the process is nearly (Surface tension of mercury is } $S$ and take $9^{2/3} = 4.326$)
Two charges +q and -q, each 1 $\mu$C are arranged as shown in the figure. If x = 2 cm and y = 3 cm then potential difference ($V_A - V_B$) is