If a number of little droplets of water, each of radius `r`, coalesce to form a single drop of radius `R`, show that the rise in temperature will be given by `(3T)/J(1/r-1/R)` where `T` is the surface tension of water and `J` is the mechanical equivalent of heat.

Options

A. `(2T)/(rJ)`
B. `(3T)/(RJ)`
C. `(3T)/(J)(1/r-1/R)`
D. `(2T)/(J)(1/r-1/R)`

Answer

C

Explanation

`Deltatheta=(3T)/(JSd)(1/r-1/R)`
`Deltatheta=(3T)/(J)(1/r-1/R)` [For water S = 1 and d = 1 ]