The surface area of a rectangular film of a liquid is extended from 10 cm xx" 6 cm to 12 m" xx 10 cm. If the work done during this process is 6 xx 10^(-4)J and surface tension of liquid is n xx 10^(-2)" N/cm", find the value of n.

The surface area of a rectangular film of a liquid is extended from 10

1.	The surface area of a rectangular film of a liquid is extended from 10 cm xx" 6 cm to 12 m" xx 10 cm. If the work done during this process is 6 xx 10^(-4)J and surface tension of liquid is n xx 10^(-2)" N/cm", find the value of n.
Answer» Solution :`triangleA=` INCREASE of area `=2(12 xx 10-10 xx 6)cm^(2)` `=120cm^(2)=120 x 10^(-4) m^(2)` Surface tension `=("WORK DONE")/("Increase in area")` `=(6 xx 10^(-4))/(120 xx 10^(-4))`