Surface tension is one of the most important and interesting properties of the fluids. Have you ever wondered why some insects like water strider can walk on water? Is it a miracle? You may have also seen light weight parts like razor blade, needle, and foil etc floating on the surface of the fluid or liquid.
Or have you ever wondered why rain falls in the form of drops or why drops of water are formed on certain surface? You may have also sometimes seen the water droplets running smoothly on the muddy surface when you blow them with slight air. Then there is popular phenomenon of the capillary action that makes the fluid in capillary at higher levels than the surrounding fluid. All these are the results of the surface tension.
Let us see some more interesting effects of the surface tension in our daily life:
1) Dew drops: Have you noticed the drops of water on the leaves in your garden in the early morning? The moisture in the atmosphere condenses in the early morning and beads on the leaves due to surface tension. The surface tension gives spherical shape to water drops.
2) Beading of water on waxed car: Waxing changes the surface properties of your car. When the rains drops fall on your waxed car, they smoothly slide down to the ground keeping your car neat and clean and untouched. Water tends to adhere weekly to the wax and strongly to itself.
3) Formation of drops from liquid: When the liquid is stretched by applying force or it is poured on some surface it tends to form the droplets due to the surface tension the fluid.
4) Mercury used in the thermometer: The mercury used in the thermometer does not stick to the wall of the capillary tube because of the surface tension. Had it stuck to the walls the measurement of temperature would not have been correct.
5) Separation of oil and water: The separation of oil and water is caused due to the difference in surface tension of the two liquids. There is also separation of the fuel and lubricating oil in the engine due to their surface tension. Had they mixed together, the fuel would have lost its combustion properties while lubricating oil would have lost its viscosity and lubrication properties.
6) Soap bubbles: Ordinarily the bubbles in water are unstable, but when surfactants are introduced in water its surface tension is reduced by factor of three or more. In such water the bubbles can remain stable; hence lots of bubbles are seen in such liquids.
Image and text source: Wikipedia