Soapy water drips from a capillary tube. When the drop breaks away, the diameter of its neck is D. The mass of the drop is `m`. Find the surface tension of soapy? Water?

Options

A. `(mg)/(pi^(2)D)`
B. `(mg)/(piD^(2))`
C. `(mg)/(piD)`
D. `(mg)/(2piD)`

Answer

C

Explanation

When the drop breaks away from the capillary weight of the drop `=` force of surface tensiton,
or `mg=piDxxT or T=(mg)/(piD)`