A capillary tube with very thin walls is attached to the beam of a balance which is then equalized. The lower end of the capillary is brought in contact with the surface of water after which an additional load of P = 0.135 gf is needed to regain equilibrium.
Determine the radius of the capillary. The surface tension of water is α = 70 dyn/cm.
Text Solution
Verified by ExpertsCHECK THE SOLUTION.
Sol. The surface tension acts on the external and internal surfaces of the tube. Considering that the tube. Considering that the walls are thin and assuming to a first approximation that the radii of the liquid surfaces near the walls of the capillary are the same in size both outside and inside the tube the forces acting on the internal and external surfaces of the tube may also be considered the same. The force acting on the internal surface is equal to the weight of the water raised into the capillary by the surface tension, while the change in the weight of the capillary is equal to twice the weight of this water.
Hence,
r = 
, r 
1.5 mm.
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems