The ratio of surface tensions of mercury and
water is given to be 7.5 while the ratio of thier
densities is 13.6. Their contact angles, with
glass, are close to 135° and 0°, respectively. It
is observed that mercury gets depressed by an
amount h in a capillary tube of radius r₁, while
water rises by the same amount h in a capillary
tube of radius r₂. The ratio, (r₁/r₂), is then close
to :