Concepts Of Physics MCQ Edition [Volume 1]PhysicsSome Mechanical Properties of Matter
A capillary tube of radius r is immersed in water, as shown in the figure. Given that the atmospheric pressure is P₀ , what is the pressure at point A ?
Options
- AP₀ + 2S r
- BP₀ - 4S r
- CP₀
- DP₀ - 2S r
Correct answer
D. P₀ - 2S r
Step-by-step solution
The pressure on the concave side of a liquid meniscus is greater than the pressure on the convex side by an amount 2S R , where S is the surface tension and R is the radius of curvature of the meniscus. For water in a capillary tube, the meniscus is concave upwards. The air is on the concave side and the liquid is on the convex side. The pressure just above the meniscus is the atmospheric pressure P₀ . Point A is located just below the meniscus, on the convex side. Assuming the angle of contact for water and glass