Question

Two vertical glass plates are held parallel 0.5mm apart, dipped in water. calculate the height to which water rises between the plates.

Answer 1

Height to which water rises between the plates is 0.0293 m.

• Here the phenomenon called capillary rise occur when two glass plates separated by a distance dipped in water.

• The height of liquid rise can be calculated by the following formula;

                                       h=(2×T×cosθ)÷(r×ρ×g)

          where;

                     T=surface tension

                     θ=angle of contact

                     ρ=density of liquid

                     g=acceleration due to gravity

                      r=radius of capillary tube or separation between glass plate

• Here water is the liquid used and distance between plates are 0.5mm.

• Surface tension of water is 72 dynes/cm and density of water is 10³kg/m³.

                                       T=72 dynes/cm=72×10⁻³ N/m

                                       ρ=10³ Kg/m³

                                       θ=0°

                                       g=9.8 m/s²

                                       r=0.5 mm=0.5×10⁻³m

               Therefore ,    h=(2×72×10⁻³×cos0)÷(0.5×10⁻³×10³×9.8)

                                         =0.0293 m