Question

A spherical soap bubble of radius $1cm$ is formed inside another bubble of radius $3cm$. The radius of single soap bubble which maintains the same pressure difference as inside the smaller and outside the larger soap bubble is -----------$cm.$

• A. $1$
• B. $0.75$
• C. $0.5$
• D. $0.25$

Answer 1

Answer: (B)

$0.75$

Excess pressure inside a soap bubble= $\frac{4T}{r}$

where $r$ is the radius of the bubble.

Hence $\frac{4T}{3}+\frac{4T}{1}=\frac{4T}{R}$

$⟹R=\frac{3\times 1}{3+1}cm$

$⟹R=0.75cm$