CBSE Class 11-Physics: Surface Tension Worksheet: Derivations (For CBSE, ICSE, IAS, NET, NRA 2022)

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Derivations and Definition-Based Problems

Question 1:

Define Surface tension and explain surface tension based on molecular theory.

Question 2:

Define Surface energy. Prove it is numerically equal to surface tension.

Question 3:

Show that a pressure difference exists between two sides of curved liquid surface.

Question 4:

Derive an expression for excess pressure

(a) Inside a liquid drop

(b) Inside a soap bubble.

Question 5:

What do you understand by the term capillarity? Give some examples of capillarity from daily life.

Question 6:

Derive an expression for the rise of liquid in capillary tube and show that the height of the liquid column supported is inversely proportional to the radius of the tube.

Numerical Based Problems

Question 1:

Calculate the work done in blowing in a soap bubble from radius to . The surface tension of the soap solution is .

(Answer:- 3770.4 erg)

Question 2:

The liquid drop of diameter D breaks up into tiny drops. Find the resulting change in energy. Take surface tension of liquid as .

(Answer:- )

Question 3:

If of work is done in blowing a soap bubble of a radius , what additional work is required to be done to blow it to a radius equal to ?

(Answer:- )

Question 4:

Soapy water drips from capillary. When the drop breaks away, the diameter of its neck is . The mass of the drop is . Find the surface tension of the soapy water. (Answer:- )

Question 5:

If the number of little droplets of water of surface tension , all of the radius , combine to form a single drop of radius R and the energy released is converted into kinetic energy, find the velocity acquired by the bigger drop.

Question 6:

What should be the pressure inside a small air bubble of radius, situated just below the surface? Surface tension of water and atmospheric pressure

Question 7:

Two soap bubbles have radii in ratio . Compare the excess pressure of liquid inside these bubbles. Also compare the works done in blowing these bubbles.

Question 8:

Water rises in a capillary tube to a height of . In another capillary tube whose radius is one-third of it, how much the water will rise?

(Answer:- )

Question 9:

A small hollow sphere having a small hole in it is immersed into water to a depth of before any water penetrates it. If the surface tension of water is dynes , find the radius of the hole.

(Answer:-

Question 10:

The maximum force, in addition to the weight required to pull a wire long from the surface of water at is dynes. Calculate the surface tension of water.

(Answer:-

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