Two Separate Air Bubbles (radii 0.002 M And 0.004 M) Formed Of The Same Liquid (surface Tension 0.07 N/m) Come Together To Form A Double Bubble. Find The Radius And The Sense Of Curvature Of The Internal Film Surface Common To Both The Bubbles. 

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Question

Two separate air bubbles (radii 0.002 m and 0.004 m) formed of the same liquid (surface tension 0.07 N/m) come together to form a double bubble. Find the radius and the sense of curvature of the internal film surface common to both the bubbles. 

Solution

Correct option is

0.004 m

 

If r1 and r2 are the radii of smaller and larger bubbles and p0 is the atmospheric pressure, the pressure inside them will be

            

Now as the pressure inside the smaller bubble will be more than inside the larger bubble, so for interface,

            

Now as excess pressure acts form concave to convex side, the interface will be concave towards smaller bubble and convex towards larger bubble (as shown in figure) and if R is the radius of interface,                      

 

   

So substituting eq. (i) and (iii) in (ii), we get 

         

So here 

         .

SIMILAR QUESTIONS

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Q3

 

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Q5

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