Surface Tesnion Experiment Questions and Answers for Viva

Answer-1: The tangential cohesive force acting along the unit length of the surface of a liquid.
T = F / L
Where, F = total force along a line
L = length of the line

Answer-2: Dynes / cm (C.G.S.) and Newton / meter (M.K.S.)

Answer-3: Cohesion force is the attractive force between like molecules, whereas, the adhesion is the attractive force between unlike molecules, e.g. attraction between glass slide and the liquid.

Answer-4: Factors affecting the surface tension are:
(a) Nature of liquid
(b) Nature of the surface in contact
(c) Temperature

Answer-5: Surface tension decreases with the rise of temperature.

Answer-6: The temperature at which the surface tension is zero.

Answer-7: The free surface of water is concave because Cohesion force between water molecules >> adhesion force between water and gas molecules. Because the free surface of mercury is convex because Cohesion force >> adhesion force.

Answer-8: The surface tension will decrease.

Answer-9: Angle of contact, for a pair of solid and liquid, id define as the angle between tangent to the liquid surface drawn at the point of contact and the solid surface inside the liquid.

Answer-10: Some practical applications of surface tension are
1. A drop of falling liquid is always in spherical shape.
2. We use oily substances to set out hairs.
3. We use soaps and detergent for cleaning clothes.
4. A thin layer of water over the umbrella protects us against light rain.
5. Capillary action e.g. rising of oil in the wick of a lamp.
6. Flying insects can walk on water surface without getting their feel wet.