Question

Two soap bubbles have radii in the ratio of 2:1. What is the ratio of excess pressures inside them?

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

Answer 1

Answer: (A)

1:02

Answer 2

Excess pressure inside the bubble, $p=\frac{4T}{r}$ Then, ${{p}_{1}}=\frac{4T}{{{r}_{1}}}$ ... (i) ${{p}_{2}}=\frac{4T}{{{r}_{2}}}$ ...(ii) From Eqs. (i) and (ii), we have $\frac{{{p}_{1}}}{{{p}_{2}}}=\frac{4T/{{r}_{1}}}{4T/{{r}_{2}}}=\frac{{{r}_{2}}}{{{r}_{1}}}$ $\frac{{{p}_{1}}}{{{p}_{2}}}=\frac{1}{2}$