Скачать или смотреть NCERT Class 11 Physics – Mechanical Properties of Fluids -Very Basic 4 | Surface Tension | JEE/NEET

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This session covers NCERT Chapter 9: Mechanical Properties of Fluids – Surface Tension (Very Basics – 5), explained in a simple, visual, and highly conceptual manner.

This video is specially designed for students preparing for:
👉 CBSE & State Boards
👉 JEE Main / JEE Advanced
👉 NEET UG
👉 CUET / BITSAT / VITEEE / WBJEE / COMEDK
👉 All other competitive entrance exams



🎯 What You Will Learn in This Video
This lecture covers all fundamental + advanced concepts of Surface Tension, including:

✔ Surface Tension (Definition + Molecular Theory)
– Why surface molecules have extra energy
– Tendency of liquids to minimize surface area
– Real-life examples and illustrations

✔ Surface Energy
– Work done in increasing surface area
– PE stored due to molecular attraction
– Energy per unit surface area explained

✔ Relation Between Surface Tension & Surface Energy
– Formula derivation
– Conceptual explanation

✔ Excess Pressure Across Curved Surfaces
– Excess pressure inside a liquid drop
– Excess pressure inside a soap bubble
– Role of radius and surface tension

✔ Angle of Contact & Wetting
– Acute vs obtuse angle of contact
– Why water wets glass but mercury does not
– Factors affecting angle of contact
– Impurity effect on angle of contact

✔ Capillarity & Capillary Rise/Depression
– Capillary action explained
– Water vs mercury behavior
– Daily-life applications

✔ Numerical Problem Solving
The session includes exam-based numericals such as:
– Work required to form bubbles
– Double bubble formation
– Coalescing water drops and energy released
– Capillary rise condition checking

Each problem is solved with clear steps and concept application to help you score high in board and competitive exams.

🧠 Why This Video is Important for Exams?
✔ Covers NCERT line-by-line concepts
✔ Suitable for revision before exams
✔ JEE/NEET-level conceptual clarity
✔ Includes high-probability numerical questions
✔ Perfect for Class 11 board preparation

More topic-wise and chapter-wise videos from Mechanical Properties of Fluids (Pressure, Laws of Floatation, Bernoulli’s Equation, Viscosity) will be uploaded soon.

00:00 – Introduction
01:10 – Surface Tension (Definition + Molecular Explanation)
02:45 – Units & Dimensions of Surface Tension
03:23 – Surface Energy
04:50 – Relation Between Surface Energy & Surface Tension
06:04 – Q. If W₁ is work required to form a bubble of volume V, find the work to form bubble of volume 2V.
MCQ:
a) 4^(2/3) W₁
b) 4^(1/3) W₁
c) 4^(1/2) W₁
d) 4^(3/2) W₁

09:46 – Two bubbles of radii 0.004 m & 0.002 m combine to form a double bubble (T = 0.07 N/m). Find internal film radius & curvature.

11:30 – Complete Solution of Double Bubble Problem

13:50 – Capillarity Introduction
Rise & fall of liquids in capillary.

15:10 – Angle of Contact
Water-glass vs mercury-glass, wetting and non-wetting surfaces.

16:15 – Numerical 3:
1000 water drops of radius 10⁻⁷ m coalesce to form one drop. Calculate energy released (T = 7.0 × 10⁻² N/m).

18:30 – Solution of Coalesced Drops Energy Problem

20:08 – Numerical 4 (Capillary Rise Decision Problem):
A 5 cm capillary tube (internal diameter = 0.1 mm) is dipped in water (T = 75 dynes/cm). State whether:
a) Water rises halfway
b) Water rises to the top
c) Water overflows
Explain the answer.

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