MCQ
A drop of liquid of diameter $2.8\, mm$ breaks up into $125$ identical drops. The change in energy is nearly ......... $ergs$ (Surface tension $= 75\, dyne/cm$)
- A$0$
- B$19$
- C$46$
- ✓$74$
✓
Answer
Correct option: D.
$74$
d
$\Delta \mathrm{E}=4 \pi \mathrm{R}^{2} \mathrm{T}\left(\mathrm{n}^{1 / 3}-1\right)$
$\Delta \mathrm{E}=4 \pi \mathrm{R}^{2} \mathrm{T}\left(\mathrm{n}^{1 / 3}-1\right)$
$=4 \times 3.14 \times\left(1.4 \times 10^{-1}\right)^{2} \times 75\left[(125)^{\frac{1}{3}}-1\right]$
$=73.85$ erg $=74$ erg
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