Question

A capillary tube of radius r is dipped in a liquid of density ρ and surface tension S. If the angle of contact is θ, the pressure difference between the two surfaces in the beaker and the capillary

• A. $\frac { S } { r } \cos \theta$
• B. $\frac { 2 S } { r } \cos \theta$
• C. $\frac { S } { r \cos \theta }$
• D. $\frac { 2 S } { r \cos \theta }$

Answer 1

Answer: (B)

$\frac { 2 S } { r } \cos \theta$

Answer 2

$S = \frac { r h d g } { 2 \cos \theta } \Rightarrow$Pressure difference

$= h d g = \frac { 2 S } { r } \cos \theta$