Surface tension

surface tension

1. Surface tension Presented By / Mohammed Ebada Ahmed Mohammed Ebada

2. Contents Mohammed Ebada

3. How we can explain? T he floating of some objects on the surface of water, even though they are denser than water and the ability of some insects (e.g. water striders) to run on the water surface. Mohammed Ebada

4. It’s surface tension effect Mohammed Ebada

5. Definition of surface tension The attractive force exerted upon the surface molecules of a liquid by the molecules beneath that tends to draw the surface molecules into the bulk of the liquid and makes the liquid assume the shape having the lest surface area. Surface tension is a property of the surface of a liquid that allows it to resist an external force Mohammed Ebada

6. How we can explain? If we put some water in one tube and some Mercury in another one , the water surface take a convex shape and the Mercury surface take a concave shape Mohammed Ebada

7. Effects of Cohesive and Adhesive Forces Mohammed Ebada

8. Cohesion force : Cohesion is the property of like molecules (of the same) to stick to each other due to substance mutual attraction. Mohammed Ebada

9. Adhesion force Adhesion is the property of different molecules or surfaces to cling to each other. Mohammed Ebada

10. When the cohesive force of the liquid is stronger than the adhesive force of the liquid to the wall, the liquid concaves down in order to reduce contact with the surface of the all. When the adhesive force of the liquid to the wall is stronger than the cohesive force of the liquid, the liquid is more attracted to the wall than its neighbors, causing the upward concavity.  Now we can understand Mohammed Ebada

11. Contact angle The contact angle is the angle, conventionally measured through the liquid, where a liquid–vapor interface meets a solid surface. Mohammed Ebada

12. Wetting Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. The degree of wetting (wettability) is determined by a force balance between adhesive and cohesive forces. Mohammed Ebada

13. Mohammed Ebada