Question

A metal wire has a circular cross section with radius 0. 800 mm. You measure the resistivity of the wire in the following way: you connect one end of the wire to one terminal of a battery that has emf 12. 0 v and negligible internal resistance. To the other terminal of the battery you connect a point along the wire so that the length of wire between the battery terminals is d. You measure the current in the wire as a function of d. The currents are small, so the temperature change of the wire is very small.

Answer 1

`\rho` = V*π*r^2/(I*d)

Step-by-step explanation:

Radius r = 0.800 mm, so Area = π x r^2

Voltage V = 12.0 V

Length = d

resistivity =
`\rho`

Current = I

Resistance R = V/I =
`\rho` * d/(π * r^2)

so

`\rho` = V*π*r^2/(I*d)