Question

When a capillary tube of radius $0.2mm$ is dipped vertically in a beaker containing water of surface tension $x.0\times {10}^{-2}$. Find $x$.

• A. 0.7
• B. 7
• C. 7.7
• D. 3.5

Answer 1

The correct option is B 7

Using formula
$h=\frac{2Tcos\theta }{\rho rg}$
= $\frac{2\times 7\times {10}^{-2}\times cos{0}^0}{1000\times 0.2\times {10}^{-3}\times 10}$
= $\frac{2\times 7\times {10}^{-3}\times 1}{0.2}(cos{0}^0=1)$
= $7\times {10}^{-2}m$
= 7 cm