Correct Answer - Option 4 : Newton / meter
CONCEPT:
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Surface tension: "It is the tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area".
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Surface tension not only depends upon the forces of attraction between the particles within the given liquid but also on the forces of attraction of solid, liquid, or gas in contact with it.
- The energy responsible for the phenomenon of surface tension may be thought of as approximately equivalent to the work or energy required to remove the surface layer of molecules in a unit area.
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Surface tension is typically measured in dynes/cm, the force in dynes is required to break a film of length 1 cm.
- Intermolecular forces such as Vander Waals force, draw the liquid.
EXPLANATIONS:
- Surface tension is defined as The ratio of the surface force F to the length L along which the force acts.
T = F/L
Where F is the force per unit length, L is the length in which force act, and T is the surface tension of the liquid.
UNIT OF SURFACE TENSION
- Unit of Force is Newton, Unit of length is meter.
\(T = F/L = N/m =Nm^{-1}\)
- The SI Unit of Force is N/m
- Hence option 4 is the correct answer.