$A$ glass capillary of radius $0.35 \ mm$ is inclined at $60^{\circ}$ with the vertical in water. The length of the water column in the capillary is (surface tension of water $= 7 \times 10^{-2} \ N/m$,acceleration due to gravity $g = 10 \ m/s^2$,$\cos 0^{\circ} = 1$,$\cos 60^{\circ} = 0.5$,density of water $\rho = 10^3 \ kg/m^3$) (in $cm$)

In a capillary tube of radius $R$,a straight thin metal wire of radius $r$ $(R > r)$ is inserted symmetrically,and one end of the combination is dipped vertically in water such that the lower end of the combination is at the same level. The rise of water in the capillary tube is $[T =$ surface tension of water,$\rho =$ density of water,$g =$ gravitational acceleration$]$.

During the capillary rise of a liquid in a capillary tube,the surface of contact that remains constant is of

$A$ capillary tube of radius $0.2\,cm$ is dipped vertically in a beaker containing liquid. If the liquid rises to a height of $5\,cm$ for which the angle of contact is $60^o$,then the surface tension of the liquid is ...... $dynes/cm$ (given density $d = 1\,gm/cm^3$ and acceleration due to gravity $g = 980\,cm/s^2$).

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 ....... $dyne/cm$.

Give reason: The lighting of a lamp is due to the wick of the lamp.