Question

A mercury drop of radius $1 \,cm$ is sprayed into $10^{6}$ drops of equal size. The energy expended in joule is (surface tension of mercury is $460 \times 10^{-3}\,N / m$ ):

• A. $0.057$
• B. $5.7$
• C. $5.7 \times 10^{-4}$
• D. $5.7 \times 10^{-6}$

Answer 1

Answer: (A)

$R =1 \,cm , n =10^{6}$
$\Delta \bigcup=4 \pi R ^{2}\left( n ^{1 / 3}-1\right) T$
$=4 \pi \times 10^{-4}\left(10^{2}-1\right) 460 \times 10^{-3}$
$=0.057\, J$