ElectrostaticsHard
Question
If ′n′ identical water drops (assumed spherical each) charged to a potential energy U coalesce to form a single drop, the potential energy of the single drop is (Assume that drops are uniformly charged):
Options
A.n1/3 U
B.n2/3 U
C.n4/3 U
D.n5/3 U
Solution
Let q is charge and a is radius of single drop. ∴ Usingle drop = 
Now, charge on big drop = nq.
& let Radius of big drop is R.
∴ By conservation of volume
⇒
∴ P.E. of big drop =
Now, charge on big drop = nq.
& let Radius of big drop is R.
∴ By conservation of volume
⇒
∴ P.E. of big drop =
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