A circular loop of a thin wire of radius `(7//pi)` cm is suspended from one arm of a balance . The plane of the loop is in contact with the surface of soap solution . If the pull on the loop due to surface tension is found to be ` 0.6 xx 10^(-3)` kg wt , then the surface tension of soap solution will be ,

Options

A. `11xx10^(-3)`N/m
B. `21xx10^(-5)`N/m
C. `21xx10^(-3)`N/m
D. `41 xx 10^(-3)` N/m

Answer

C

Explanation

` T = F/(2xx2pir)=(6xx10^(-4)xxpixx10)/(4xxpixx7xx10^(2))=21 xx10^(-3) ` N/m