A long capillary tube of radius 2 mm open at both ends is filled with water and placed vertically, What will be the height of the coluum of water left in the capillary ? The thickness of the capillary walls is negligible. Surface tension of water is `73.5 xx 10^(-3)Nm^(-1)`

Answer

1.5 cm

Explanation

The column of liquid of length h remaining in the tube will be held by two meniscus as shown in
if R is the radius of the liquid meanisus and S is the surface tension of liquid, then. `4S//R = h rhog or h = 4S//g R rho` if r is the radius of the capillary tube and angle of contact between water - glass surface is zero `(i.e., theta = 0^@)` then `R = r//cos theta =r = 2mm = 2xx10^(-3)m`
`:. h = (4xx73.5xx10^(-3))/(9.8 xx2x10^(-3)xx 10^3)`
` =1.5 xx10^(-2) = 1.5 cm`