Q.

A capillary tube of radius 0.1 mm is partly dipped in water (surface tension 70 dyn/cm and glass water contact angle 0°) with 30° inclined with vertical. The length of water risen in the capillary is _____ cm. (Take g = 9.8 m/s2)          [2025]

1 825  
2 572  
3 715  
4 685  

Ans.

(1)

h=2T cos θρgr=2×70×11×980×102=1007 cm

sin 60°=hl  l=h×23

l=1007×23=2007×3=16.49 cm