To Determine the Surface Tension of Water by Capillary Rise Method Viva Questions with Answers

Surface tension is the tendency of liquid surfaces at rest to shrink to the minimum feasible surface area. 

• Surface tension permits objects with a higher density than water, such as razor blades and insects (such as water striders), to float on the water's surface without being submerged.
• This liquid characteristic is based on the fact that the molecules of the liquid at the surface are in a different state from those in the liquid's center. 
• The molecule at the liquid surface is surrounded by other molecules and attracts in all directions equally. 
• As a result, the molecule's net attraction force is zero. 
• Surface tension is determined not only by the forces of attraction between particles, but also by the forces of attraction of solids, liquids, and gases in close contact with it.

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Ques. What is Capillary action?

Ans. Capillary action is the process by which a liquid flows in a narrow space without the help of, or even in opposition to, external forces such as gravity.

Ques. What is capillarity?

Ans. The tendency of a liquid to rise or fall as a result of surface tension in a capillary tube or absorbent material.

Ques. What is a capillary tube?

Ans. Capillary tubes are commonly observed in labs, industries, and homes.

It is a cylindrical tube with a fixed diameter that can hold any gas, liquid, or solid particles.

Ques. Define tension.

Ans. Tension is a force along the length of a medium, particularly one that is produced by a flexible medium such as a rope or cable.

Ques. What is surface tension?

Ans. Surface tension is described as the tension of a liquid's surface film caused by the bulk of the liquid's attraction to the particles in the surface layer, which tends to minimize surface area.

Ques. Give an example where we can witness surface tension.

Ans. Surface tension is most clearly demonstrated by the walking of insects on water and liquid droplet shapes.

Ques. What is the surface tension of water?

Ans. Water has a surface tension of 0.07275 joules per square meter at 20 °C (68 °F).

Ques. What is the formula to calculate the surface tension of water?

Ans. The formula for calculating water surface tension is:

\(T= \frac{r(r+h/3) \rho g}{2cos \theta}\)

Ques. How is surface tension measured?

Ans. Surface tension is usually measured in dynes per cm.

Ques. What is the SI unit of surface tension?

Ans. Surface Tension is measured in Newton per Metre (N/m) in the SI unit.

Ques. What is the CGS unit of surface tension?

Ans. Dyn/cm is the surface tension unit used in the CGS system.

Ques. What causes insects to float on water?

Ans. Because of a phenomenon called surface tension, insects may walk on water. In simple terms, this is a characteristic of water (or any liquid) that enables it to withstand an external force. Water molecules set up bonds with other molecules, and those that have been exposed to air on one side will do so in a much stronger manner than those that have not. Insects can technically walk on water since they are small and lack enough force to push their way through.

Ques. Can the surface tension of water support a razor blade?

Ans. Since a razor blade has a higher density than water, it may be sustained by the surface tension of the liquid.

Ques. What would be the shape of the meniscus when the contact angle is greater than 90 degrees?

Ans. When the contact angle is more than 90 degrees, the meniscus would have a convex shape.

Ques. What are the various types of forces due to which the liquid rises?

Ans. The various types of forces due to which the liquid rises are

• Cohesion
• Adhesion
• Surface tension

Ques. Define cohesion.

Ans. In physics, cohesion refers to the intermolecular attraction that exists between two adjacent parts of a material, especially one that is solid or liquid.

Ques. Define adhesion.

Ans. Adhesion is the intermolecular attraction that exists between different kinds of molecules.

Ques. Give an example of adhesion.

Ans. Adhesion may be seen when the glass surface becomes wet from water. This is caused by the intermolecular interactions between the glass and the water.

Ques. Explain the relationship between surface tension and surface energy.

Ans. The following is the relationship between surface tension and surface energy:

Surface Energy = Surface tension x Change in area

Ques. Which side of the liquid surface has more pressure?

Ans. The pressure is greater on the free liquid surface's concave side.

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