Question

A long capillary tube of radius $1mm$, open at both ends is filled with water and placed vertically. What will be the height of water column left in the capillary ? (Surface tension of water is $73.5\times {10}^{-3}N.m^{-1}$)

• A. $0.3cm$
• B. $3cm$
• C. $6cm$
• D. $0.03cm$

Answer 1

Answer: (B)

$3cm$

$\text{Remaining weight water = force due to surface tension.}$

$\pi r^{2}h\rho g=2\times 2\pi r\cos \theta$

$h=0.03\text{m}=3\text{cm}$