MCQ
The work done in doubling the radius of a soap bubble of radius $2\,cm$ will be ( $S.T.$ of soap solution $= 30\,dyne/cm$ )
- ✓$9.043\times 10^3\,erg$
- B$4.521\times 10^3\,erg$
- C$2.695\times 10^3\,erg$
- D$1.507\times 10^3\,erg$
✓
Answer
Correct option: A.
$9.043\times 10^3\,erg$
a
$w=2 T \Delta A$
$w=2 T \Delta A$
$\mathrm{w}=60\left(4 \pi \mathrm{r}_{2}^{2}-4 \pi \mathrm{r}_{1}^{2}\right)$
$w=60 \times 4 \pi(16-4)$
$w=60 \times 4 \pi \times 12$
$\mathrm{w}=9.043 \times 10^{3} \mathrm{erg}$
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