Question

The resistance of a wire a length 250m is 1 ohm. If the resistivity of wire is $1.6\times {10}^{-8}$ ohm meter. Find area of cross section of the wire.

Answer 1

$R=\rho$ $l/A$

$\rho =$ resistivity of wire

$l=$ length

$A=$ Area of cross $-$ selection

$1=1.6\times {10}^{-8}\times \frac{250}{A}$

$A=4\times {10}^{-6}{m}^2$.