Question

A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of water in the capillary tube is 5 g. Another capillary tube of radius 2r is immersed in water. The mass of water that will rise in this tube is:

• A. 2.5 g
• B. 5.0 g
• C. 10 g
• D. 20 g

Answer 1

Answer: (C)

10 g

$h=\frac{\left(2Tcos\theta \right)}{R\rho g}$

Thus, $h\alpha \frac{1}{R}$ ...............(1)

Now $M=\left(\pi R^{2}h\right)\rho$

So, $M\alpha R^{2}h$ .................(2)

So, combining equations 1 and 2,

$M\alpha R$

So, doubling the radius will also double the mass of water will be doubble.

So, the mass of water $=5g\times 2=10g$

Option C is correct.