GATE Electrical Engineering (EE) 2017 Shift 2 Solved Paper

A thin soap bubble of radius, R = 1 cm and thickness a = 3.3 μm (a ≪ R), is at a potential of 1 V with respect to a reference point at infinity. The bubble bursts and becomes a single spherical drop of soap (assuming all the soap is contained in the drop) of radius r. The volume of the soap in the thin bubble is 4πR²a and that of the drop is $\frac{4}{3}\mathit{\pi }{\mathit{r}}^3$. The potential in volts, of the resulting single spherical drop with respect to the same reference point at infinity is ________. (Give the answer up to two decimal places.)