The surface tension of a soap solution is 30×10−3Nm−1. The work done in stretching a bubble of this solution of surface area 5cm×5cm, to an area of 10cm×10cm, is

A
$4.5 \times 10^{- 4} J$
B
$6.0 \times 10^{- 4} J$
C
$4.5 \times 10^{- 5} J$
D
$7.5 \times 10^{- 4} J$

Solution:

Work done

$\begin{array}{l} = 2 (A_{2} - A_{1}) \times S \\ = 2 (10 \times 10 - 5 \times 5) \times 10^{- 4} m^{2} \times 30 \times 10^{- 3} {Nm}^{- 1} \\ = 4.5 \times 10^{- 5} J . \end{array}$

The surface tension of a soap solution is $30 \times 10^{- 3} {Nm}^{- 1}$ . The work done in stretching a bubble of this solution of surface area $5 cm \times 5 cm$ , to an area of $10 cm \times 10 cm$ , is

Solution:

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