1. What do you mean by cohesive force and adhesive force?
The force on any two molecules of same substance is called cohesive force.
The adhesive is the force which acts on two molecules of different substances is called adhesive force.
2. Define surface tension, surface energy and angle of contact.
Surface Tension: The tangential force per unit length on a liquid surface that acts along the normal on either side of an imaginary line on that surface is called surface tension.
The surface energy of a liquid is measured by the work done to increase the area of the surface of a liquid by unity.
If W be work done to increase the area of the surface of the liquid by A, the surface energy E=W/A
Angle of contact: When a surface of a liquid comes in contact with a solid, it becomes curved near the place of contact. The angle inside the liquid between the tangent to the solid surface and to the liquid surface is called angle of contact.
3. Write down the expression for the rise of liquid column in a capillary tube.
The expression for the rise of liquid column in a capillary tube is
h=\frac{2TCos\theta }{r \rho g}
T= surface tension of the liquid
\theta = angle of contact
\rho = density of the liquid
g= acceleration due to gravity r=radius of the capillary tube
4. What is Jurin’s law?
rh=Constant
h is the rise of liquid column in a capillary tube of radius r
5. Does surface depend on temperature?
Yes, surface depends on temperature.
Surface tension decreases with increase in temperature.
6. Does surface depend on impurity?
Yes, impurity decreases the surface tension of the liquid.