Two soap bubbles of radii r1 and r2 equal to 4 cm and 5 cm are touching each other over a common surface S 1 S 2 (shown in figure). Its radius will be :-

Question

Two soap bubbles of radii r1 and r2 equal to 4 cm and 5 cm are touching each other over a common surface S 1 S 2 (shown in figure). Its radius will be :- (A) 4 cm. (B) 20 cm. (C) 5 cm. (D) 4.5 cm

Tardigrade Admin · Accepted Answer

P1-P2=(4 T/r) ⇒ (4 T/r1)-(4 T/r2)=(4 T/r) ⇒ r=(r1 r2/r2-r1) r=(r1 r2/r2-r1)=(4 × 5/5-4) cm . =20 cm

Q. Two soap bubbles of radii $r_{1}$ and $r_{2}$ equal to $4 c m$ and $5 c m$ are touching each other over a common surface $S_{1} S_{2}$ (shown in figure). Its radius will be :-

4 cm.

20 cm.

5 cm.

4.5 cm

$P_{1} - P_{2} = \frac{4 T}{r}$
$\Rightarrow \frac{4 T}{r _{1}} - \frac{4 T}{r _{2}} = \frac{4 T}{r}$
$\Rightarrow r = \frac{r _{1} r _{2}}{r _{2} - r _{1}}$
$r = \frac{r _{1} r _{2}}{r _{2} - r _{1}} = \frac{4 \times 5}{5 - 4} c m$ .
$= 20 c m$

Q. Two soap bubbles of radii r1​ and r2​ equal to 4cm and 5cm are touching each other over a common surface S1​S2​ (shown in figure). Its radius will be :-