Question

Work done in forming a soap bubble of radius R is W. Then work done is forming a soap bubble of radius $2$R will be

• A. $42W$
• B. $4$W
• C. $\frac{W}{2}$
• D. $\frac{W}{4}$

Answer 1

Answer: (B)

$4$W

Work done in forming soap bubble = T$\times Area$

W = $T\times 4\pi r^2$

W $\propto r^2$

so

$\frac{W_1}{W_2}=\frac{r_1^2}{r_2^2}$

$W_2=W_1\times (\frac{2r}{r}{)}^2$ = 4W

hence option B is the correct answer