The amount of work done to form a soap bubble of radius $5 \mathrm{~cm}$ from a soap solution is nea

Question

The amount of work done to form a soap bubble of radius $5 \mathrm{~cm}$ from a soap solution is nearly (surface tension of soap solution $=0.04 \mathrm{~N} \mathrm{~m}^{-1}$)

Professor PC Thomas Classes · Answer

(c) : The work done (energy required) to form a soap bubble is given by $W = T 	imes \Delta A$. Since a soap bubble has two free surfaces (inner and outer), the area is $\Delta A = 2 	imes 4\pi r^2 = 8\pi r^2$. Substituting the values: $W = 0.04 	imes 8 	imes 3.14 	imes (5 	imes 10^{-2})^2 = 0.04 	imes 25.12 	imes 25 	imes 10^{-4} = 25.12 	imes 10^{-4} \mathrm{~J} \approx 25.1 	imes 10^{-4} \mathrm{~J}$.