Q. 5

# A liquid is contained in a vertical tube of semicircular cross section (figure 14-Q5). The contact angle is zero. The force of surface tension on the curved part and on the flat part are in ratio

A. 1 : 1

B. 1 : 2

C. π : 2

D. 2 : π

Answer :

The surface tension is defined as the enhancement of the intermolecular force at the surface of the fluid. It is mathematically expressed as,

Thus the force exerted by the molecules on the surface is equal to S.L.

The surface tension on the curved part is

F = S.πr

Where r is the radius of the curved tube and S is the surface tension of the liquid.

The force exerted as a consequence of the surface tension on the flat portion of the tube,

F’ = S.2r

Therefore, the ratio of the forces of surface tension on the curved part and on the flat surface;

Hence option C is the correct answer.

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