Question

Two soap bubbles each with radius \(r_1\) and \(r_2\) coalesce in vacuum under isothermal conditions to form a bigger bubble of radius \(R\). Then \(R\) is equal to

• A. \(\sqrt{r_1^2 + r_2^2}\)
• B. \(\sqrt{r_1^2 - r_2^2}\)
• C. \(r_1 + r_2\)
• D. \(\frac{\sqrt{r_1^2 + r_2^2}}{2}\)
• E. \(2\sqrt{r_1^2 + r_2^2}\)

Hint:

In a vacuum under isothermal conditions, simply remember that the square of the final radius is the sum of the squares of the individual radii: \(R^2 = \sum r_i^2\).

Answer 1

The Correct Option is A