plzz help..

detail soln..

E for an infinitly long conducter ...

let @ be charge density ////

drawing a cylindrical gaussian surface of radius r and length l .........

@l/e = 2 pi r l E ....

@/2 pi e r = E .....

now we have two of them of chargedensity say @ , -@

E(at r) = @/2 pi e r + @/2 pi r (b-r) ...

V = -∫E.dr !!

takin origin at 1 of the conducters ..

V(a) - V(b-a) = -@/2pie [2ln(a/b-a)]

@/pie [ln(b-a/a)]

now q in 1 unit length ........ @(1) /

C = Q/V ...
@pi e/@ln(b-a/a)

pi e /ln(b-a/a)...

as b>>a

pi e / ln(b/a)