Question

The tube of a mercury barometer is 1 cm in diameter. What correction due to capillarity is to be applied to the barometric reading if the surface tension of mercury is 435.5 dyn/cm and the angle of contact of mercury with glass is 140° ? [Density of mercury = 13600 kg/m³]

Answer 1

Data : d = 1 cm, T = 435.5 dyn/cm, θ = 140°, ρ = 13660 kg/m³ = 13.66 g/cm³ ,

g = 9.8 m/s² = 980 cm/s²

∴ The correction due to capillarity = -0.1001 cm