JEE Main & Advanced Physics Fluid Mechanics, Surface Tension & Viscosity / द्रव यांत्रिकी, भूतल तनाव और चिपचिपापन Question Bank Surface Energy

  • question_answer
    What is ratio of surface energy of 1 small drop and 1 large drop, if 1000 small drops combined to form 1 large drop  [CPMT 1990]

    A) 100 : 1

    B)                       1000 : 1

    C)             10 : 1  

    D)              1 : 100

    Correct Answer: D

    Solution :

                    Volume of liquid remain same i.e. volume of 1000 small drops will be equal to volume of one big drop             \[n\frac{4}{3}\pi {{r}^{3}}=\frac{4}{3}\pi {{R}^{3}}\]Þ\[1000{{r}^{3}}={{R}^{3}}\]Þ\[R=10r\]\[\therefore \frac{r}{R}=\frac{1}{10}\]             \[\frac{\text{surface energy of one small drop}}{\text{surface energy of one big drop}}=\frac{4\pi {{r}^{2}}T}{4\pi {{R}^{2}}T}=\frac{1}{100}\]


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