Question

In increasing the area of the film of soap solution from 50cm^2to 100cm^2,3.0×10^-4J of work is done.calculate the value of surface tension of the soap

Answer 1

S=3×10^-4/ (100-50)×10^-4=3/50 J/m^2

Answer 2

The value of surface tension of the soap is 0.06 N/m.

We know, surface tension (S) is given as:

S = W / ΔA

where W is the work done and,

ΔA is the change in area.

Given in the question,

W = 3 × 10⁻⁴ J

and ΔA = Final area - Initial area = (100 - 50) cm² = (50 × 10⁻⁴) m².

[1 cm = 10⁻² m and so, 1 cm² = 10⁻⁴m²]

Thus

S = (3 × 10⁻⁴) / (50 × 10⁻⁴) N/m = 3/50 N/m = 0.06 N/m.