A wire with conductivity carries a steady current I. Confirm the statement made in the text

A wire with conductivity σ carries a steady current I. Confirm the statement made in the text that a charge Q ∼ = ϵ₀ I/σ accumulates on the wire’s surface in the immediate neighborhood of a 90◦ right-angle bend. Make a sketch of the wire indicating the position and sign of the surface charges. Explain the physical origin of the algebraic sign of the charges that you draw.