27 similar drops of mercury are maintained at 10V each. All these spherical drops combine into a single big drop. The potential energy of the bigger drop is ________times that of a smaller drop.

Using conservation of volume,Initial Vol = Final Vol⇒2743πr3=43πR3⇒R=3rPotential  of small drop, Vs=kqr=10 V (given)Self- potential energy of a small drop=US=35kq2rSelf- potential energy of big drop=UB=35kQ2RThus, UBUS=Qq2×rR=27qq2×r3r=243⇒UB=243US