Question
A mercury drop of radius 1 cm is sprayed into 10^{6} droplets of equal size. Calculate the energy expended if surface tension of mercury^{*} is .

None of these



medium
Solution
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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