# Is Pascal's law incorrect?

Consider the figure given below.

Here I'm gonna talk about capillarity. The liquid inside the beaker as well as the column is water. As water has a tendency to rise in the capillary as shown, doesn't it violate Pascal's law.

At equilibrium when water has risen in the tube, pressure at point A as well as the pressure at water surface which is open to atmosphere will be $1$ $atm$. In turn pressure at point B will be $1$ $atm$ as it is at the same level above the ground as water in beaker ( Pascal's law ). Which means that $P_a-P_b$ is zero but according to Pascal's law it should have been $h\rho g$.

What's wrong then.

• Pressure at Point A(just inside liquid) is less than a point just above it. The discontinuity is due to the phenomenon of surface tension due to which the pressure across the meniscus is different.(Pressure suffers discontinuity at the meniscus) Aug 26, 2018 at 16:27
• Again, asking "Is this well-established law incorrect?" appeals to me as a drastically bad question. It's much more reasonable to ask how a certain law can be applied to the given situation. Can you edit the title?
– user191954
Sep 2, 2018 at 6:10

As stated in the comments, the pressure at B is (approximately) equal to atmospheric pressure, so Pascal's law holds. The pressure in the tube above B is lower than atmospheric ($p_a=p_b-\rho gh$). The difference in pressure between the liquid and the atmosphere at A is compensated by the force of surface tension at the meniscus.