Surface tension of water is 0.072 `Nm^(-1)`. The excess pressure inside a water drop of diameter 1.2 mm is:

Options

A. 240 `Nm^(-1)`
B. 72 `Nm^(-1)`
C. 60 `Nm^(-1)`
D. 120 `Nm^(-1)`

Answer

A

Explanation

Excess pressure inside the drop is,
`P=(2s)/(r)=(4s)/(d)`
`=(4xx0.072)/(1.2xx10^(-3))=240Nm^(-2)`