A 1.40 m cylindrical rod of diameter 0.550 cm is connected to a power supply that maintains a constant potential difference of 16.0 V across its ends, while an ammeter measures the current through it. You observe that at room temperature (20.0 ∘C) the ammeter reads 18.7 A , while at 92.0 ∘C it reads 17.2 A . You can ignore any thermal expansion of the rod.