Solids Fluids

Work done in increasing the size of a soap bubble from a radius of 3 cm to 5 cm is nearly. (Surface tension of soap solution = 0.03 Nm-1)

  1. 0.2π mJ
  2. 0.4π mJ
  3. 2π mJ
  4. 4π mJ

Answer

W = TΔA

= 0.03 (2 x 4π x (52 - 32)10-4)

= 24π(16) x 10-6

= 0.384π x 10-3 Joules

≈ 0.4π mJ

The correct option is B.