Q.

Three small identical bubbles of water having same charge on each coalesce to form a bigger bubble. Then the ratio of the potentials on one initial bubble and that on the resultant bigger bubble is :   [2026]

1 32/3:1  
2 1:31/3  
3 1:22/3  
4 1:32/3  

Ans.

(4)

Using volume conservation

3(43πr3)=(43πR3)

R=31/3r

ViVf=kqrk(3q)R=R3r=31/3r3r=132/3