Mercury has an angle of contact equal to 140° with soda lime glass. A narrow tube of radius 1.00 mm made of this glass is dipped in a trough containing mercury. By what amount does the mercury dip down in the tube relative to the liquid surface outside? Surface tension of mercury at the temperature of the experiment is 0.465 N m–1. Density of mercury = 13.6 × 103 kg m–3.

Surface tension is related with both angle of contact and dip in the height as,


Where,


h = dip height


ρ = density = 13.6 × 103 kg/m3


g = acceleration due to gravity = 9.81 m/s


r = radius of the dipped tube = 1 × 10-3 m


θ = contact angle = 1400


and, Surface Tension S = 0.465 N/m


Thus, height of dip down,




= -0.00534 m


= -5.34 mm


Negative sign indicates decrease in level of mercury in tube. Hence the mercury level is dipped by 5.34 mm.


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