JEE Mains · Physics · STD 11 - 9.2 surface tension
A liquid column of height \(0.04 \mathrm{~cm}\) balances excess pressure of soap bubble of certain radius. If density of liquid is \(8 \times 10^3 \mathrm{~kg} \mathrm{~m}^{-3}\) and surface tension of soap solution is \(0.28 \mathrm{Nm}^{-1}\), then diameter of the soap bubble is _______ \(\mathrm{cm}\). \(\text { (if } g=10 \mathrm{~ms}^{-2} \text { ) }\)
- A \(8\)
- B \(7\)
- C \(6\)
- D \(9\)
Answer & Solution
Correct Answer
(B) \(7\)
Step-by-step Solution
Detailed explanation
\(\rho g h=\frac{4 S}{R}\) \(\Rightarrow R=\frac{4 \times 0.28}{8 \times 10^3 \times 10 \times 4 \times 10^{-4}}\) \(\Rightarrow \frac{0.28}{8} \mathrm{~m}=\frac{28}{8} \mathrm{~cm}\) \(\Rightarrow R=3.5 \mathrm{~cm}\) \(\text { Diameter }=7 \mathrm{~cm}\)
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