The angle of contact in case of a liquid depends upon A. the nature of the liquid and the solid B. the material which exists above the free surface of the liquid C. both of die above D. any one of the above

the nature of the liquid and the solid
the material which exists above the free surface of the liquid
both of die above
any one of the above

The correct answer is C. both of the above.

The angle of contact is the angle between the tangent to the liquid surface and the solid surface at the point of contact. It depends on the following factors:

  • The nature of the liquid and the solid. The surface tension of the liquid and the solid’s surface energy determine the angle of contact.
  • The material which exists above the free surface of the liquid. If there is a gas above the liquid, the angle of contact will be different than if there is a solid above the liquid.

The angle of contact is important in many applications, such as ink-jet printing, coating, and lubrication.