Question

In a capillary tube, water rises by 1.2 mm. The height of water that will rise in another capillary tube having half the radius of the first, is:-

• A. 1.2 mm
• B. 2.4 mm
• C. 0.6 mm
• D. 0.4 mm

Answer 1

Answer: (B)

2.4 mm

The capillary rise in a tube is given by,

H = $\frac{2Tcos\theta }{\rho gr}$

Therefore, the height rise in a capillary tube is inversely proportional to the radius of the tube.

Hence, for all other parameters constant, $H\propto r^{-1}$

So, if radius is halved, the capillary rise will double,i.e $2.4$ mm in this case