Question

A conductor of length 100cm and area of cross section 1mm^(2) carries a current of 5A .If the resistivity of the material of the conductor is 3×10^(-8)Ohm- m . then the electric field across the conductor is

Answer 1

Since the voltage is $U=E\times l$ , where $E$ is the electric field strength and $l$ is the length of the conductor (in this case). Since the conductor resistance is $R=\frac{\rho \times l}{S}$ , where $\rho$ - resistivity, $l$ - length of the conductor, and $s$ is the cross-sectional area, according to Ohm's law $U=I\times R$ , then $E=\frac{U}{l}=\frac{I\times\frac{\rho \times l}{S}}{l}=\frac{5\times 3\times10^{-8} }{1}=15\times10^{-8}$ V.