A 1.50 m cylindrical rod of diameter 0.500 cm is connected to a power supply that maintains a constant potential difference of 12.0 V across its ends, while an ammeter measures the current through it. You observe that at room temperature (20.0 ∘C) the ammeter reads 18.2 A , while at 92.0 ∘C it reads 17.4 A . You can ignore any thermal expansion of the rod. Part A Find the resistivity for the material of the rod at 20 ∘C. Part B Find the temperature coefficient of resistivity at 20 ∘C for the material of the rod.