Prove that if two bubbles of radii `r_(1)` and `r_(2)(r_(1)ltr_(2))` come in contact with each other then the radius of curvature of the common surface `r=(r_(1)r_(2))/(r_(2)-r_(1))`

Options

A. `r_(2)-r_(1)`
B. `(r_(2)-r_(1))/(r_(1)r_(2))`
C. `(r_(1)r_(2))/(r_(2)-r_(1))`
D. `r_(2)+r_(1)`

Answer

C

Explanation

Radius of curvature of common surface is,
`R_("Common")=(r_(1)r_(2))/(r_(2)-r_(1))`