The surface tension of soap solution is 0.03 N/m. The work done in blowing to form a soap bubble of surface area 40 cm², in joules is

Options

(a) 1.2×10⁻⁴
(b) 2.4×10⁻⁴
(c) 12×10⁻⁴
(d) 24×10⁻⁴

Correct Answer:

2.4×10⁻⁴

Explanation:

Given: Surface tension of a soap solution,
T = 0.03 N/m
Surface area, A = 40 cm² = 40 x 10⁻⁴ m²
Since the soap has two surfaces,
.·. Work done, W = T x 24
= 0.03 x 2 40 x 10⁻⁴ = 2.4 x 10⁻⁴J