A1.60 m cylindrical rod of diameter 0.550 cm is connected to a power supply that maintains a constant potential difference of 17.0 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 17.3 a . you can ignore any thermal expansion of the rod.

part a

find the resistivity and 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.

2) an 18-gauge copper wire (diameter 1.02 mm) carries a current with a current density of 1.90×106 a/m2 . copper has 8.5×1028 free electrons per cubic meter.

part a

calculate the current in the wire.

express your answer using two significant figures.

part b

calculate the drift velocity of electrons in the wire.

express your answer using two significant figures.