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How Surface Tension Works? (in Hindi)
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Surface tension force, explanation behind the origins of this force with mathematical analysis of the same. Theory is supported with an example to better understand the topic.

Udit Gupta is teaching live on Unacademy Plus

Udit Gupta
A Mechanical Engineer from NIT Allahabad here to help learners with physics. Also a Star ⭐ educator.

U
Unacademy user
Sir, ther is no more updates on CA after 25th June,18. Its been 2 weeks. Kindly do update. Thank you.
check the July course..
Aarthi A
a year ago
Okay, Sir.
Sir, surface tension tangential kyo hota hai?
Udit Gupta
4 months ago
Kyuki surface tension name says itself that it is the tension arising on the surface.
Rupam Khound
3 months ago
still! why isn't the tension normal to the surface and only tangential ?
AK
sir, sin( d theta/ 2) = d theta/2 ,then and comes T = 2 sigma R??
Udit Gupta
9 months ago
haan wo sigma by R hi hoga. sorry for the calculation mistake.
AK
sir, for small angle - sin theta ~theta, so sin (dtheta/2)~ dtheta /2 ,then T = 2sigmaR ???
Ps
last problem 3 bar dekha fir be samaj nahi aa raha aur easy way me samajvyo
Udit Gupta
9 months ago
Aise socho ki aapka haath is the film. Toh uske 2 surface hain, ek upar knuckles wala part and niche hatheli (palm) wala part
hello sir muje aapki first lesson jisme apne how to work surface tention me last vala example samj me nai aayo can you explain in easy way this example plzz reply
Udit Gupta
10 months ago
s.t. ki force tries to pull the loop and hence forms a circle. This is the only concept you need to apply. This in turn develops a tension force in the loop due to pulling.
  1. SURFACE TENSION : DEFINTION AND PRACTICALITY Udit Gupta Alumnus MNNIT Allahabad EX-VMC faculty of physics Ex-Cofounder, Elements-Azamgarh


  2. INSIDE THIS LESSON What is surface tension? Reasons behind surface tension ath in surface tension Solved Examples


  3. WHAT IS SURFACE TENSION 2 The property of a liquid due to which an object can be kept on its surface without wetting the object is known as surface tension This type of force can be compared to a stretched balloon This is the property due to which: (ii) A (ii) A stietched membrone as in o mosguio omtonwoler surface pin can be kept on water surface flat stone thrown jumps parallel to the surface of a lake (rebounds)


  4. REASONS BEHIND SURFACE TENSION The main reason why the properties of surface differ as compared to that of bulk can be easily explained by the diagram shown. A molecule which is in bulk, i.e. surrounded by same molecules all on sides is different from a mo which is surrounded by two different types of molecules on juxtapose sides. This couses unbolance in forces acting on molecules on surface lecule


  5. MATH IN SURFACE TENSION Generally the surface tension force acts in a layer of 10-15 molecules deep from the surface this depth, equal forces start acting on the molecules After The force between two molecules decrease as the separation distance increases For an imaginary line AB on the surface of the liquid, the sutace tension torce octs proporionol to the length of AB. It has a pulling effect


  6. MATH BEHIND SURFACE TENSION This force and acts perpendicular to paralel to the surface of the liquid the line AB where, is called surface tension F is the force and I is the length AB


  7. MATH BEHIND SURFACE TENSION The unit of surface tension is The dimension of surface tension is [MT-]. in case of a liquid surface, surface tension force is 1. liquid bubble or liquid film force is 2/l


  8. EXAMPLE If a loop lying on a thin soap film as shown, is pricked, find the tension in the loop finally. The length of the loop is L. The surface tension of the film is . prick loop


  9. SOLUTION As soon as the flm is pricked. the surface tension forces (pulling) act on the loop and it expands to form a circle. To calculate the tension in the loop, we can considero shown. a small part of loop Tcos(de/2) Tcos(de/2) Tsin(de/2) de Tsin(de/2)


  10. SOLUTION From the FBD we can say; 2Tsin (2/-2 ( For small angle, des Rde) [Front and rear film] ol 2