Question

Water rises in a capillary tube when its one end is dipped vertically in it, is 3 cm. If the surface tension of water is $75\times {10}^{-3}$ N/m, then the diameter of capillary will be

• A. 0.1 mm
• B. 0.5 mm
• C. 1.0 mm
• D. 2.0 mm

Answer 1

The correct option is C

1.0 mm

$T=\frac{rh\rho g}{2}\Rightarrow 75\times {10}^{-3}=\frac{3\times {10}^{-2}\times r\times {10}^3\times 9.8}{2}$

$\Rightarrow r=\frac{1}{2}mm\therefore D=2r=1mm$