Question

The potential energy possessed by a soap bubble, having surface tension equal to 0.04 N/m of diameter 1 cm, is

(a) 6π x 10-6 J

(b) 2π x 10-6 J

(c) 8π x 10-6J

(d) 4π x 10-6 J.

Answer 1

Correct option (c) 8π x 10-6J

Explanation :

Given = Surface tension in soap bubble

(T) = 0.04 N/m and diameter of soap bubble

(d) = 1 cm = 0.01 m or radius (r) = 0.005 m.

Potential energy = surface tension x surface area. For a soap bubble, there are two surfaces. Therefore total area = 2 x 4πr2

Thus potential energy