Relation between surface tension and viscosity?

Surface tension is the amount of attraction the surface of an object has. Surface tension is easily demonstrated by observing a pool of water. Put your finger in the water and slowly… i mean “slowly”… pull your finger away and you will see the water is actually attracted to your finger and the water will stay on your finger as you pull your finger off the pool of water. This is because of surface tension.

Viscosity is the resistance of a liquid flow. A high viscosity means the liquid is thicker and does not move as readily. (And technically solids have an infinite viscosity because they do not “flow”). A high viscous liquid would be like syrup. A low viscous liquid would be like water.

Now… a high viscous liquid (like syrup) has a higher surface tension than a low viscous liquid. Do the “finger” demonstration with syrup. You will notice that syrup (being more viscous) will actually be attracted to your finger more than water is. Once you put your finger in a pool of syrup and bring it out… more syrup will be still on your finger.

If you relate the water and syrup demonstration you will see that a higher viscosity means a greater surface tension and a lower viscosity means a lower surface tension.

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