Question

Surface tension of a soap solution is `1.9xx10^(-2) N//m`. Work done in blowing a bubble of 2.0 cm diameter will be
A. `45.54 pi xx 10^(6)` J
B. `15.2 pi xx 10^(-6)`J
C. `1.9 pi xx10^(-6)`J
D. `1 pi xx 10^(-4)`J

Answer 1

Correct Answer - B
`dw = S.T xx "surface area "`
` = 1.9 xx10^(-2) xx (4piR^(2)) xx 2 `
`= 1.9 xx 10^(-2) 4xx pi (1 xx 10^(-2))xx2`
` = 15.2 xx10^(-6) pi ` J