The sap in a tree rises in a system of capillaries of radius $2.5 \times 10^{-5} \, m$. The surface tension of the sap is $7.28 \times 10^{-2} \, N \, m^{-1}$ and the angle of contact is $0^{\circ}$. The maximum height to which the sap can rise in a tree through capillarity action is ...... $m$ (take $\rho_{sap} = 10^3 \, kg \, m^{-3}$ and $g = 9.8 \, m \, s^{-2}$).

Water rises to a height of $16.3 \,cm$ in a capillary tube. If the tube is cut at a height of $12 \,cm$ above the water level,what will happen?

Mercury has an angle of contact equal to $140^{\circ}$ with soda lime glass. $A$ narrow tube of radius $1.00 \; mm$ made of this glass is dipped in a trough containing mercury. By what amount does the mercury dip down (in $mm$) in the tube relative to the liquid surface outside? Surface tension of mercury at the temperature of the experiment is $0.465 \; N m^{-1}$. Density of mercury $= 13.6 \times 10^{3} \; kg m^{-3}$.

Why is the refill of a marker pen used to write on a whiteboard made of fibers?

Two narrow bores of diameter $5.0 \, mm$ and $8.0 \, mm$ are joined together to form a $U$-shaped tube open at both ends. If this $U$-tube contains water,what is the difference in the level of two limbs of the tube? [Take surface tension of water $T = 7.3 \times 10^{-2} \, Nm^{-1}$,angle of contact $= 0$,$g = 10 \, ms^{-2}$ and density of water $\rho = 1.0 \times 10^{3} \, kg \, m^{-3}$] (in $mm$)

In a vessel, equal masses of alcohol (specific gravity $0.8$) and water are mixed together. A capillary tube of radius $1 \, mm$ is dipped vertically in it. If the mixture rises to a height of $5 \, cm$ in the capillary tube, the surface tension of the mixture is ....... $dyne/cm$.