Single-phase electricity at 240 V and 50Hz is sometimes transmitted via concentric cables. The conductor of diameter d₁ passes at the center of the cable and acts as the live wire, while the concentric neutral of diameter d₂ surrounds the live conductor. Red PVC separates the two conducting materials, and black PVC is used as the jacket as shown in the simple image below. Calculate the inductance of a 1 m long wire when d₁ = 5.10 mm and d₂ = 10.5 mm.