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Course: Class 11 Physics (India) - Hindi > Unit 8
Lesson 5: Surface tension (Hindi)Surface Tension and Adhesion (Hindi)
Ram explains the concepts of surface tension, cohesion, and adhesion. Created by Ram Prakash.
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I performed similar experiment and got same results but after some time i observed that needle is moving towards the sides of the glass,Why this happened?
Thanks in advance(3 votes)
THREE possibilities:
1. Wind causing this (most probable cause)
2. The water was moved by pre-motion of glass or the table on which the glass was kept. (Or maybe the table is not straight)
3. (most interesting and the basic practical proof of Brownian motion of fluid, although it's visible for very light objects like pollen grain on wateror smoke in a closed glass jar, i don't know if needle can be moved solely due to Brownian motion) Now let's say there's NO wind or any kind of source moving the glass, if u observe carefully, u'd see light objects still moving on surface of water. That's because of the constantly moving of extremely tiny water molecules (we can't directly see those) which make the object move as well.(2 votes)