Question

The surface tension of water at ${20}^{\circ }C$ is 75 $\times {10}^{-3}$N/m. The difference in the water surfaces within and outside an open-ended capillary tube of 1 mm internal bore, inserted at the water surface would nearly be

• A. 5 mm
• B. 10 mm
• C. 15 mm
• D. 20 mm

Answer 1

The correct option is C 15 mm

$d=1\times 2=2mm\Delta h=\frac{4\sigma }{d{\gamma }_w}=\frac{4\times 75\times {10}^{-3}}{2\times {10}^{-3}\times 9.81\times 1000}$

= 0.015 m = 15 mm