Question

Calculate the density of paraffin oil, if in a glass capillary of diameter 0.25 mm dipped in paraffin oil of suface tension 0.0245 N/m, the oil rises to a height of 4 cm. [angle of contact of paraffin oil with glass = ${28}^o$ and acceleration due to gravity = $9.8m/s^2$]

Answer 1

$h=\frac{2T\cos \theta }{r\rho g}$
$\rho =\frac{2T\cos \theta }{hrg}$
$\rho =\frac{2\times 0.0245\times \cos 28}{0.04\times 0.25\times {10}^{-3}\times 9.8}$
$\rho =882\frac{kg}{m^3}$