Question

The energy needed in breaking a drop of radius $R$ into $n$ drops of radius $r$ is

• A. $(4\pi r^{2}n-4\pi R^2)T$
• B. $(4\pi R^2-4\pi r^2)T$
• C. $[\frac{4}{3}\pi r^3-\frac{4}{3}\pi R^3]T$
• D. $(4\pi R^2-n4\pi r^2)/T$

Answer 1

Answer: (A)

$(4\pi r^{2}n-4\pi R^2)T$

Energy $=$ Surface tension $\times$ Area

$Ei=T\left({4\pi R}^2\right)$

$E_f=nT\left({4\pi r}^2\right)$

Energy required $=E_f-Ei$

$=T(4{\pi r}^2\eta -4\pi R^2)$