Question

The ratio of radius of two bubbles is $2:1$. What is the ratio excess pressure inside them?

• A. 1:02
• B. 1:04
• C. 2:01
• D. 4:01

Answer 1

Answer: (A)

1:02

Answer 2

The excess pressure inside the bubble $p=\frac{4 T}{r}$ Then, $p_{1}=\frac{4 T}{r_{1}} \dots$(i) $p_{2}=\frac{4 T}{r_{2}}\dots$(ii) From Eqs. (i) and (ii) $\frac{p_{1}}{p_{2}}=\frac{\frac{4T}{r_{1}}}{\frac{4 T}{r_2}}=\frac{r_{2}}{r_{1}}$ $\frac{p_{1}}{p_{2}}=\frac{1}{2}$