Question

The resistance of a wire of lenghth 250m is 1 ohm and resistivity is 1.6*10 to the power -8 ohm m. Find area of cross section

Answer 1

$r = sl \div a \\ 1 = 1.6 \times {10}^ - {8 \times 250 \times \div a \: \: }$
a=400*(10)-8 metre square