Question 128 of 192

A soap bubble of the radius $3cm$ is formed inside another soap bubble of radius, $6cm$. The radius of an equivalent soap bubble that has the same excess pressure as inside the smaller bubble with respect to the atmospheric pressure is____$cm.$

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Answer: 2

The formula of excess pressure inside the soap bubble is, $\dfrac{4T}{R}$ here $T$ is the surface tension and $R$ is the radius of the soap bubble,

$\Rightarrow {P}_{0}+\dfrac{4T}{6}+\dfrac{4T}{3}={P}_{0}+\dfrac{4T}{R}$
$\Rightarrow \dfrac{1}{6}+\dfrac{1}{3}=\dfrac{1}{R}$$\Rightarrow R=2cm$.