Question Detail
Question
A liquid of density 1.05 g/cm³ and contact angle 20° has a vertical capillary tube of 2 mm diameter dipping into it. If the surface tension is 235 dynes/cm, and g = 980 cm/s², what is the rise of the liquid in cm? (Calculate based on given data)
Correct Answer
Option B is the correct answer.
Detailed Explanation
Using h = (2γ cosθ) / (ρ g r). Given: γ = 235 dyne/cm, θ = 20°, ρ = 1.05 g/cm³, g = 980 cm/s², diameter = 2 mm so radius r = 1 mm = 0.1 cm. cos 20° ≈ 0.9397. h = (2 × 235 × 0.9397) / (1.05 × 980 × 0.1) = (441.659) / (102.9) ≈ 4.29 cm.
Hint
Substitute the values into the capillary rise formula, ensuring consistent units (all in CGS).