Introduction
We observe many things in our day-to-day life. Surface Tension Phenomenon is one among them. Often we confuse the Phenomena of Surface tension with Buoyancy. Both the phenomena are entirely different to each other in the sense, in Buoyancy a portion of the body gets dipped in the liquid whereas in Surface tension the body will be remaining on the layer of water without getting wet.
Let us observe these leaves on the surface of water. We could see them moving in the water without getting wet.
For these leaves to be on the layer, there should be some force acted by the upward layer of water which keeps the leaf on the surface. This is nothing but the Surface tension. Let us study more about the Surface tension in this section.
What is Surface Tension?
The Surface tension is defined as: The dragging force observed in the given liquid per unit length. It is given by the formula:
T = FL
where,
F = Force per unit length
L = Length over which the force acts.
The Surface tension is expressed in Newton per meter.
What causes Surface Tension?
Surface tension is a physical property of water. Here the cohesive force keeps the water intact. Each molecule in the beaker is pulled in every direction equally by adjacent molecules.
Let us observe the following diagram:
The dragging force acts between the each molecules by the other molecule. Therefore the resulting net force is zero.
At the surface of water in a beaker, the water molecule does not have another water molecule around the sides of them. Therefore creation of internal pressure. Water molecules at the surface are pulled inwards. Top layer of liquid surface of beaker are compressed to minimum area.
Effects of Surface Tension
Several effects of surface tension can be seen with ordinary water:
A. Beading of rain water on a waxy surface, such as a leaf. Water adheres weakly to wax and strongly to itself, so water clusters into drops. Surface tension gives them their near-spherical shape, because a sphere has the smallest possible surface area to volume ratio.
B. Formation of drops occurs when a mass of liquid is stretched. The animation shows water adhering to the faucet gaining mass until it is stretched to a point where the surface tension can no longer bind it to the faucet. It then separates and surface tension forms the drop into a sphere. If a stream of water was running from the faucet, the stream would break up into drops during its fall. Gravity stretches the stream, then surface tension pinches it into spheres…
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