Two equally charged soap bubbles of equal volume join together to form a large bubble. If each small bubble had a potential V, find the potential of the resultant bubble.

Explanation

Let radius of each small bubble be r, charge be Q and radius of large bubble be R.
`(4)/(3) piR^3= 2xx(4)/(3)pir^3 " or " R = 2^(1/3)*r`
Potential of each small bubble,
`V= (Q)/(r )" or " Q= Vr`
Potential of the large bubble `=(" total charge ")/(" radius ") = (2Q)/(R ) = (2Vr)/(2^(1/3)r)= 2^(2/3)V`.