(i) When the radius of wire is r1
R1 = ρ (l / A1)
R1 = ρ (l / πr12)
(ii) When the radius of wire is r2
R2 = ρ (l / A2)
R2 = ρ (l / πr22)
∴ R1: R2 will be
ρ (l / πr12) : ρ (l / πr22)
= r22: r12
(ii) Because the two wires are made of the same material, their resistivity will be the same. That is
ρ1: ρ2 = 1: 1