Tiêu đề 1.4 Surface tension.pdf ✅

Unit 1 1.4 Surface Tension

SURFACE TENSION • The phenomenon of surface tension is explained by Fig. • Consider three molecules A, B, C of a liquid in a mass of liquid. • The molecule A is attracted in all directions equally by the surrounding molecules of the liquid. Thus the resultant force acting on the molecule A is zero. • But the molecule B, which is situated near the free surface, is acted upon by upward and downward forces which are unbalanced. Thus a net resultant force on molecule B is acting in the downward direction. • The molecule C, situated on the free surface of liquid, does experience a resultant downward force. All the molecules on the free surface experience a downward force. Thus the free surface of the liquid acts like a very thin film under tension of the surface of the liquid act as though it is an elastic membrane under tension.