University:
North Idaho College
Course:
PHYS-211 | Engineering Physics I
Academic year:

2023
Views:

32

Pages:

5
Author:

Hani T.

Surface Tension: Surface Tension is a property of liquids. related to the intermolecular forces. Consider figure shown, A and B we Molecules of a liquid A is surrounded on all sides by other molecules. B on the other hand on the surface, exposed to air. B clearly experiences forces on three sides but none from air. A is subject to equal forces on all sides. The unbalanced attractive force on B Lends To Pull the Surface Molecule inward and the Surface od the liquid Contracts to the smallest possible Area. Molecular forces. in liquid Surface Energy This accounts for the spherical Shape of draps of liquid or bubbles in a liquid This Tendency to Contract causes The liquid Surface to be under Tension and this phenomenon is known as Surface Tension Surface Tension is defined as the force in dynes acting at Right Angles along the surface of a liquid along a 1cm length of Surface It is represented in dynes or N/m being a measure of the force required to increase the distance by 1 cm or 1m , and is designated by Y Surface Tension acts parallel to the Surface Pressure which opposes any attempt to extend interface. A tension is a Negative pressure, pressure is a force per unit Area $0 that surface pressure is a force per unit length. dA = 2 (l x dl) = r x 2 (h x del F is the force γ x 2 (l x dl) = F x dl 2 γ l = F γ = F / 2l = Force / Length