Question

Two soap bubbles of radius 2 cm and 4 cm, respectively, are in contact with each other. The radius of curvature of the common surface, in cm, is _______________.

Hint:

The radius of curvature of the common surface of two soap bubbles in contact is calculated using the formula $r = \frac{r_1 \cdot r_2}{r_1 - r_2}$.

Answer 1

Correct Answer: 4

For two soap bubbles in contact, the radius of curvature $r$ of the common surface is given by: $$r = \frac{r_1 \cdot r_2}{r_1 - r_2}$$ where $r_1 = 4 \, \text{cm}$ and $r_2 = 2 \, \text{cm}$: $$r = \frac{2 \times 4}{4 - 2} = \frac{8}{2} = 4 \, \text{cm}$$ Thus, the answer is $\boxed{4}$.