Question

The surface tension of a liquid is 5 N/m. If a thin film of the area 0.02 m2is formed on a loop, then its surface energy will be?
//in One of the byju's video they derived that
surface energy = surface tension
then what is happening in the question
Surface tension is already given then why it is messing up with area and asking for surface energy ?

Answer 1

Total surface area, A=2×0.02 m²=[multiplied with 2..because film has two surfaces ]=0.04 m²
surface tension, T=5 N/m
Surface energy, E=T×A=5×0.04=0.2 J

For your doubt about surface energy = surface tension, it is true only if the area is 1,other wise it is not true..because surface energy is given by E=T×A