Surface Tension, it’s unit and applications

Surface Tension, it’s unit and applications

Surface Tension:-

It is the property of fluid tries to shrink into minimum surface area and enables to resist tensile stress. It is define as the surface Tension force per unit length.

Surface Tension= Force/Length σ = F/L SI Unit of Surface Tension= N/m MKS unit of Surface Tension= Kg/s2 CGS unit of Surface Tension= gm/s2 Dimension of Surface Tension = MT-2

Important point :-

• In equilibrium condition fluid are not able to sustain surface Tension.
• at critical point of temperature or at boiling point the surface Tension is zero.
• Surface Tension do not depend on pressure.
• Spherical shape posses minimum surface area.
• Mosquito can sit on the free surface on liquid due to this property.

Applications of Surface Tension:-

• Manufacture of lead shots.
• Water Bubbles or water droplet
• Formation of Soap Bubbles
• Destruction of mosquito breeding
• Liquid Jet.

Here are 10 daily life examples of surface tension:

1. Water droplets on a car windshield: Rainwater forms into small droplets due to surface tension.
2. Floating paperclip: When placed gently on the surface of water, a paperclip can float due to surface tension.
3. Meniscus in a graduated cylinder: The curved shape of water in a graduated cylinder is due to surface tension.
4. Soap bubbles: The spherical shape of soap bubbles is maintained by surface tension.
5. Water striders: These insects can “walk” on water due to surface tension.
6. Capillary action in plants: Surface tension helps water move up plant stems against gravity.
7. Insect repellent on water: When sprayed on water, insect repellent forms a film due to surface tension.
8. Needle floating on water: If carefully placed, a needle can float on water’s surface due to surface tension.
9. Water clinging to a glass: Water droplets can cling to the sides of a glass due to surface tension.
10. Water beading on a freshly waxed car: After waxing a car, water beads up on the surface due to surface tension.

Value of Surface Tension for some Important elements:-

Elements	Surface Tension (in N/m)
Water	.0725
Mercury	.485
Benzene	.0289
Acetone	23.7
Ethanol	22.7

Frequently Asked Questions:

 

1. An iron needle floats on the surface of water. this phenomenon is attributed to

A) Surface tension
B) Gravitational Force
C) Upthrust of liquid
D) None of the above

ANSWER= (A) Surface tension
Explain:-
Check Answer

 

2. Surface tension of a liquid is due to ?

A) Adhesive force between molecules
B) Cohesive force between molecules
C) Gravitational force between molecules
D) Electrical force between molecules

ANSWER= (B) Cohesive force between molecules
Explain:-
Check Answer

 

3. Some insects like water strider is able to walk on the surface of water due to

A) Viscosity
B) Capillary rise
C) Surface tension
D) Gravitational force

ANSWER= (C) Surface tension
Explain:-
Check Answer

 

4. Rain drops are spherical in shape. this due to

A) Evaporation
B) Viscosity of water
C) Air friction
D) Surface tension

ANSWER= (D) Surface tension
Explain:-
Check Answer

 

5. The Force per unit length is the unit of

A) Surface tension
B) Viscosity
C) Compressibility
D) Capillarity

ANSWER= (A) Surface tension
Explain:-
Check Answer

 

6. The unit of surface tension is ?

A) N/m^2
B) N-m
C) N/m
D) N/m^3

ANSWER= (C) N/m
Explain:-
Check Answer

 

7. The surface tension of mercury at normal temperature is______ that of water.

A) Higher than
B) Lower than
C) same as
D) None of these

ANSWER= (A) Higher than
Explain:-
Check Answer

 

8. Select the correct dimensions for surface tension among the following.

A) J/m
B) Nm
C) W/m^2
D) J/m^2

ANSWER= (D) J/m^2
Explain:-
Check Answer

 

9. Ball pen works on the principle of

A) Boyle’s law
B) Viscosity
C) Gravitational force
D) Surface tension

ANSWER= (D) Surface tension
Explain:-
Check Answer

 

10. The rise of a liquid in a capillary tube is due to

A) Diffusion
B) Viscosity
C) Surface tension
D) Osmosis

ANSWER= (C) Surface tension
Explain:-
Check Answer

Read Also-

• Fundamental quantities and its units
• Force, its types and its units
• Motion and it’s type
• Pressure and it’s Unit
• Surface Tension and it’s applications
• Explanations of elasticity and Hooke’s law
• Heat transfer and Modes of heat transfer

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