JEE Main 2026 Physics question
If an air bubble of diameter 2 mm rises steadily through a liquid of density 2000 kg/m³ at a rate of 0.5 cm/s, then the coefficient of viscosity of liquid is Poise. (Take g = 10 m/s²)
Answer: (B)
Solution
η = 2r²gρ/(9v) (neglecting air density) = 2(10⁻³)²(10)(2000)/(9 × 0.005) = 0.04/0.045 ≈ 0.889 Pa·s = 8.89 Poise ≈ 8.8 Poise.