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:
- Water droplets on a car windshield: Rainwater forms into small droplets due to surface tension.
- Floating paperclip: When placed gently on the surface of water, a paperclip can float due to surface tension.
- Meniscus in a graduated cylinder: The curved shape of water in a graduated cylinder is due to surface tension.
- Soap bubbles: The spherical shape of soap bubbles is maintained by surface tension.
- Water striders: These insects can “walk” on water due to surface tension.
- Capillary action in plants: Surface tension helps water move up plant stems against gravity.
- Insect repellent on water: When sprayed on water, insect repellent forms a film due to surface tension.
- Needle floating on water: If carefully placed, a needle can float on water’s surface due to surface tension.
- Water clinging to a glass: Water droplets can cling to the sides of a glass due to surface tension.
- 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
Explain:-
2. Surface tension of a liquid is due to ?
Explain:-
3. Some insects like water strider is able to walk on the surface of water due to
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4. Rain drops are spherical in shape. this due to
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5. The Force per unit length is the unit of
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6. The unit of surface tension is ?
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7. The surface tension of mercury at normal temperature is______ that of water.
Explain:-
8. Select the correct dimensions for surface tension among the following.
Explain:-
9. Ball pen works on the principle of
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10. The rise of a liquid in a capillary tube is due to
Explain:-
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