Q.

A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of the water in the capillary is 5 g. Another capillary tube of radius 2r is immersed in water. The mass of water that will rise in this tube is              [2020]

1 2.5 g  
2 5.0 g  
3 10.0 g  
4 20.0 g  

Ans.

(3)

Force of surface tension balances the weight of water in capillary tube.

          Fs=Tcosθ (2πr)=mg

m∝r

Hence, m'm=r'r ⇒ m'5 g=2rr ⇒ m'=10g