Question

Two large glass plates are placed vertically and parallel to each other inside a tank of water with separation between the plates equal to 1 mm. find the rise of water in the space between the plates. Surface tension of water = 0.075 N m^-1.

• A. 0.015 cm
• B. 1.5 mm
• C. 15 cm
• D. 1.5 cm

Answer 1

The correct option is D

1.5 cm

The situation can be depicted as,

Let the side of this assumed square plate be 'a' now upward force due to surface tension = 2Sa as two layers are in contact with two sides.

Ignoring the weight of the water contained in meniscus as it is very small

Volume of water contained I capillary =$a\times d\times H\{length\times width\times Height\}$
$\Rightarrow$ weight of water contained =$\rho$ a d H g
For the fluid contained in the capillary to be in equilibrium,
$\rho$ a d H g=2 S a
$H=\frac{2S}{\rho dg}$
Substituting the values,
$H=\frac{2\times 0.075}{1000\times 1\times {10}^{-3}\times 10}m$
0.0150m=1.5cm