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Capillary Action MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 25, 2023 25:23 PM | #NEET

Quick Facts

  • Rise of liquid in a capillary tube is considered one the most difficult concept.

  • 22 Questions around this concept.

Solve by difficulty

20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator, the length (in cm) of the water column in the capillary tube will be :

Concepts Covered - 1

Rise of liquid in a capillary tube
  •  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 \rho  (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 h=2TcosΘρgr

where 

T - sur face Tension
r - radius of capillary tube
ρ - liquid density
θ - Angle of contact
1. The capillary rise depends on the nature of liquid and solid both. I.e on T,ρ,θ,r
2. For a given liquid and solid pair as T,ρ,θ are constat then hα1r. 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 Θ<90 (1.e for water and capillary tube of glass)

So Meniscus will take Concave shape and liquid in the capillary will rise/ascend.
II. For Θ>90 (I.e for Mercury and glass capillary tube)

So Meniscus will take Convex shape and liquid in the capillary will fall/descend.
III. For Θ=90 (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.

 


 

 

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Rise of liquid in a capillary tube

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