A ring of radius R is having two charges `q` and `2q` distributed on its two half parts. The electric potentiasl at a point on its axis at a distance of `2sqrt2 R` from its centre is `(k=1/(4piepsilon_0))`

Explanation

Distance of P from periphery of ring is

`sqrt(R^2+(2sqrt(2)R)^(2))=3R`
Electric potential = Potential due to upper half + Potential due to lower half
`=(Kq)/(3R)+(2Kq)/(3R)implies(3Kq)/(3R)=(Kq)/(R)`