An electrical conductor designed to carry large currents has a circular cross-section `2.50 mm` in diameter and is `14.0 m` long. The resistance between its ends is `0.104 Omega` .
(a) What is the resistivity of the material?
(b) If the electric field magnitude in the conductor is `1.28V//m`, what is the total current?
(c) If the material has `8.5 x 10^28` free electrons per cubic metre, find the average drift speed under the conditions of part (b).

Answer

A, B, C

Explanation

a. `rho=(RA)/l=((0.104)(pi//4)(2.5xx10^-3)^2)/14`
`=3.65xx10^-8Omega-m`
`b. V=El=1.28xx14=17.92V`
`:. i=V/R=17.92/0.104=172.3A`
`c. v_d=i/("ne"A)`
`=172.3/((8.5xx10^28)(1.6xx10^-19)(pi/4)(2.5xx10^-3)^2)`
`=2.58xx10^-3m//s`