Question

calculate the resistance of a copper wire of 50m long and diameter 1 mm

Answer 1

d=1mm
area=22/7 ×1/100m×1/100m

$= \frac{\pi}{10000} m$
$r = p \frac{l}{a}$
$p = 1.7 \times {10}^{ - 8}$
$r = \frac{1.7 \times {10}^{ - 8} \times 50 \times 7 \times {10}^{4} }{22}$
$r = 595 \times {10}^{ - 4} \div 22 \\ = 27.05 \times {10}^{ - 4}$