A Mercury Drop Of Radius 1 Cm Is Sprayed Into 106 droplets Of Equal Size. Calculate The Energy Expended If Surface Tension Of Mercury* is .

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Question

A mercury drop of radius 1 cm is sprayed into 106 droplets of equal size. Calculate the energy expended if surface tension of mercury* is .

Solution

Correct option is

 

If a drop of radius R is sprayed into n droplets of equal radius r, then as a drop has only one surface, the initial surface area will be  while final area . So the increase in area

        

So energy expended in the process.  

          

Now since the total volume of n droplets is the same as that of initial drop, i.e.,  

           

So substituting the value of r from eq. (ii) in (i), 

            

So here,  

       

            .

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