Question

courant et resistance: problem 1 (1 point) lorsque 160 v est appliqué à un fil de longueur 35 m et de rayon 1.4 mm, un courant de 5 a le traverse. trouvez la résistivité du matériau. ω·m

Explanation:

Step1: Find the resistance using Ohm's law

According to Ohm's law $R=\frac{V}{I}$, where $V = 160$ V and $I=5$ A. So $R=\frac{160}{5}=32$ $\Omega$.

Step2: Find the cross - sectional area of the wire

The cross - sectional area of a circular wire $A=\pi r^{2}$, with $r = 1.4$ mm $=1.4\times10^{- 3}$ m. So $A=\pi\times(1.4\times10^{-3})^{2}\approx6.16\times10^{-6}$ m².

Step3: Use the resistance formula to find resistivity

The resistance formula is $R=
ho\frac{l}{A}$, where $l = 35$ m, $R = 32$ $\Omega$ and $A\approx6.16\times10^{-6}$ m². Rearranging for $
ho$, we get $
ho=\frac{RA}{l}$. Substituting the values: $
ho=\frac{32\times6.16\times10^{-6}}{35}\approx5.6\times10^{-6}$ $\Omega\cdot$m.

Answer:

$5.6\times10^{-6}$