1.

Small mercury drops of the same size are charged to the same potential V. If n such drops coalesce to form a single large drop, then calculate its potential.

Answer»

Solution :Let r be the radius of a small DROP and R that of the large drop. Then, since the volume remains conserved,
`(4)/(3) pi R^(2)= (4)/(3) pi r^(2) n "" rArrR^(3) = r^(3) n `
R = `r^(3) (n)^(1//3)`
Further, since the total CHARGE remains conserved, we have using Q = CV
`C_("large") V = n C_("small"^(V))`
Where V is the potential of the large drop.
`4 pi epsilon_(0) RV = n (4 pi epsilon_(0) r)_(v)`
V= `("nrv")/(R) = ("nrv")/(r(n)^(1//3))`
`V = vn^(2//3)`


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