A 1.70 m cylindrical rod of diameter 0.450 cm is connected to a power supply tha

Question

A 1.70 m cylindrical rod of diameter 0.450 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 17.1 A . You can ignore any thermal expansion of the rod.
A)Find the resistivity and for the material of the rod at 20 C.
B)Find the temperature coefficient of resistivity at 20 C for the material of the rod.
Will rate thanks.

Explanation / Answer

A)

V = IR

17 = 18.7 R

R = 0.909 ohm

resistivity xL/A = R

resistivity = 0.000008504 ohm m

B)

V = I1 R1

R1 = 0.994 ohm

R1-R/R = alpha x delta T

alpha = 0.00129 /K

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