Question

Water rise in a capillary upto a extension height such that upward force of surface tension balances the force $75\times {10}^{-4}N$. due to weight of water. If surface tension of water $6\times {10}^{-2}N/m$. The internal circumference of the capillary must be :-

• A. $12.5\times {10}^{-2}m$
• B. $6.5\times {10}^{-2}m$
• C. $0.5\times {10}^{-2}m$
• D. $10.5\times {10}^{-2}m$

Answer 1

Answer: (A)

$12.5\times {10}^{-2}m$

$F=T\left(2\pi r\right)$

$F/T$ = circumference

$75\times {10}^{-4}/6\times {10}^{-2}$ = circumference

circumference = $12.5\times {10}^{-2}m$