An arc of radius r carries charge. The linear density of charge is λ and the arc subtends an angle π3 at the centre. What is electric potential at the centre?
Length of the arc = rθ=rπ3
Charge on the arc = rπ3×λ
∴ Potential at center = kqr
=14πϵ0×πr3λr=λ12ϵ0