Practice question
Question
A capillary tube of radius 0.2mm is dipped in mercury (S\=0.4355N/m, ρ\=13.6×103kg/m3, cosθ\=−0.5). What is the depression? (Take g\=10m/s2)
Explanation
Capillary rise: h = 2Scosθρga. S = 0.4355N/m, ρ = 13.6×103kg/m3, g = 10m/s2, a = 0.2×10−3m, cosθ = −0.5. h = 2×0.4355×(−0.5)13.6×103×10×0.2×10−3 = −0.016m = −1.6cm. As per NCERT, applying relevant law/formula with correct units and sign convention leads to -1.6 cm. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.