JEE Main 2024 Physics question
A liquid column of height 0.04 cm balances excess pressure of soap bubble of certain radius. If density of liquid is 8 × 10³ kg m⁻³ and surface tension of soap solution is 0.28 Nm⁻¹, then diameter of the soap bubble is cm. (if g = 10 ms⁻²)
Answer: 7
Solution
4S/R = ρgh ⇒ R = 4 × 0.28/(8000 × 10 × 4 × 10⁻⁴) = 0.035 m = 3.5 cm, so the diameter is 7 cm.