An isolated soap bubble is kept in a container in which the pressure is maintained at $P_0$. The bubble is given some charge due to which its radius increases to $r$ and the pressure inside the bubble reduces to $P_0$. If the surface tension of the soap bubble is $T$, then the charge given to the bubble is

• A

  $Q=8\pi r\sqrt{rT{\epsilon }_0}$
• Correct answer
  B

  $Q=8\pi r\sqrt{2rT{\epsilon }_0}$
• C

  $Q=4\pi r\sqrt{2rT{\epsilon }_0}$
• D

  $Q=4\pi r\sqrt{rT{\epsilon }_0}$

Hence, the correct answer is option: 'B'.