Skip to main content

Surface Tension

Surface tension

It is the force of attraction(cohension) between the similar surface particles of fluid which forms films .

Reasons : various forces such as vanderwaal forces , hydrogen bonding forms web of water molecules on the surface.

Concept :
At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). The net effect is an inward force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. 

Eg. A. Ants and other spinder walk through surface of water.
   
   B. Rain drop has a  shape

Additional Information :
Its dimension is same as that of force per unit length

Water has surface tension of 72.8 milli newtons at 20 degree centigrade

Labels:

Comments

Post a Comment

Popular posts from this blog

Wire drawing effect

Wire drawing effect : It is erosion or scoring of valve seat and disc material of the valve . Causes : 1. Due to differential pressure across the valve . 2. Thermal and mechanical damages . Effects : Valve is unable to isolate the line and fails in sealing . Gas and liquid will leak from the wire and scratch like groove .
Post a Comment
Read more

Cross and loop scavenging Disadvantage

Cross scavenging Disadvantage 1. It requires longer  piston skirt to prevent exhaust gas and air leaks from the ports when piston is at TDC . Loop scavenging Disadvantage 1. Both exhaust port and scavenge port are at the adjacent side of the liner which causes temperature differential problem for the liner material . Hence , we are using mostly the uniflow scavenging which is having very lesser mixing and better scavenging efficiency. Source : DA Taylor
Post a Comment
Read more