Capillary Action - Practice Questions & MCQ

•  Capillarity -

If a capillary tube is dipped in a liquid, it is found that the liquid in the capillary either ascends or descends relative to the surrounding liquid. This phenomenon is called capillarity.

 Examples of capillarity-

1. A towel soaks water.

• Ascent Formula-

When one end of the capillary tube of radius r is immersed into a liquid of density   (For example- water and capillary tube of glass), And the shape of the liquid meniscus in the tube becomes concave upwards as shown in the figure.

Then the height h up to which the liquid level rises in the capillary tube  is given by Ascent Formula 

which says 

where 

1. The capillary rise depends on the nature of liquid and solid both. I.e on   
2. For a given liquid and solid pair as  are constat then  .   i.e., lesser the radius of capillary greater will be the rise and vice-versa.
3. Capillary action for various liquid-solid pair

         I. For   ( I.e for  water and capillary tube of glass)

             So Meniscus will take Concave shape and liquid in the capillary will rise/ascend.

        II.  For    ( I.e for  Mercury and glass capillary tube)

             So Meniscus will take Convex shape and liquid in the capillary will fall/descend.

      III.  For     ( I.e for  Pure water and silver-coated capillary tube.)

             So Meniscus will take Plane shape and liquid in the capillary will show No rise, no fall.