Assume that a drop of liquid evaporates by decrease in its surface energy, so that its temperature remains unchanged. What should be the minimum radius of the drop for this to be possible ? The surfrace tension is T, density of liquid is p and L is its latent heat of vaporization.

Options

A. `sqrt(T//pL)`
B. `T//pL`
C. `2T//pL`
D. `pL//T`

Answer

C

Explanation

`p4piR^(2)DeltaRL=T4pi[R^(2)-(R-DeltaR)^(2)]`
`pR^(2)DeltaRL=T[R^(2)-R^(2)+2RDeltaR-DeltaR^(2)]`
`pR^(2)DeltaRL=T2RDeltaR`(`DeltaR` is very small)
`R=(2T)/(pL)`
So, correct . choice is ( c)