Calculate the work done agains surface tension in blowing a soap bubble from a radius 10 cm to 20 cm if the surface tension of soap solution is `25xx10^(-3)N//m` then compare it with liquid drop of same radius.

Explanation

For soap bubble : Extension in area
`=2xx(4pir_(2)^(2)-4pir_(1)^(2))=8pi[(0.2)^(2)-(0.1)^(2)]`
`=0.24pim^(2)`
Work done`W_(1)`= surface tension `xx` extension in area `=25.0xx10^(-3)xx0.24pi=6pixx10^(-3)J`.
For Liquid Drop : in case of liquid drop there is only one free surface, so extension in area will be half that of soap bubble.
`:.W_(2)=(W_(1))/(2)=3pixx10^(-3)J`