Question

Two capillary tubes of diameter $5mm$ and $4mm$ are held vertically inside water one by one. How much high the water will rise in each tube (Given $g=10m/s^2$ and surface tension of water = $7\times {10}^{-2}N/m^2)$)

• A. $5mm$ and $7mm$
• B. $5.6mm$ and $7mm$
• C. $12mm$ and $5mm$
• D. $10mm$ and $5.6mm$

Answer 1

The correct option is B $5.6mm$ and $7mm$

We know that

$h=\frac{2T}{{\rho }_{g}r}$

So

$H_1=\frac{2\times 7\times {10}^{-2}}{{10}^3\times 10\times \frac{5}{2}\times {10}^{-3}}=5.6\times {10}^{-3}$

$H_2=\frac{2\times 7\times {10}^{-2}}{{10}^3\times 10\times \frac{4}{2}\times {10}^{-3}}=7\times {10}^{-3}$

Answer:- (B)