Question

A liquid of density $\rho$ and surface tension rises in a capillary tube of inner radius $R$. The angle of contact between the liquid and the glass is $\theta$ The point A lies just below the meniscus in the tube and the point B lies at the outside level of liquid in the beaker as shown in figure. The pressure at $A$ is

• A. $P_B-\rho gh$
• B. $P_B-\frac{2\sigma \cos \theta }{R}$
• C. $P_{atm}-\frac{2\sigma \cos \theta }{R}$
• D. All of these

Answer 1

The correct option is D All of these

Radius of meniscus$=\frac{R}{\cos \theta }=r$
$\Delta P$ due to spherical surface$=\frac{2\sigma }{r}=\frac{2\sigma \cos \theta }{R}$
$P_B=P_{atm}$