MCQ
A soap bubble, having radius of $1\; \mathrm{mm}$, is blown from a detergent solution having a surface tension of $2.5 \times 10^{-2}\; N / m$. The pressure inside the bubble equals at a point $Z_{0}$ below the free surface of water in a container. Taking $g=10\; \mathrm{m} / \mathrm{s}^{2}$ density of water $=10^{3} \;\mathrm{kg} / \mathrm{m}^{3},$ the value of $\mathrm{Z}_{0}$ is......$cm$
  • A
    $100$
  • B
    $10$
  • $1$
  • D
    $0.5 $

Answer

Correct option: C.
$1$
c
$P=P_{0}+\rho g Z_{0}\ldots(i)$

Also, $\mathrm{P}=\mathrm{P}_{0}+\frac{4 \mathrm{T}}{\mathrm{R}}\ldots$ (ii)

From $(i) \;and\; (ii)$

$\rho g Z_{0}=\frac{4 \mathrm{T}}{\mathrm{R}}$

$\mathrm{z}_{0}=\frac{4 \mathrm{T}}{\mathrm{pgR}}$

$=\frac{4 \times 2.5 \times 10^{-2}}{10^{3} \times 10 \times 10^{-3}}=10^{-2} \mathrm{m}=1 \;\mathrm{cm}$

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