According to the question,
R = 1 ohm
Specific resistance = 1.7× 10-8 ohm m
r = 10-3 m
l =?
R = ρ 1 / A
l = RA / ρ
l = Rπr2 / ρ
l = (1 × π × 10-6) / (1.7 × 10-8)
l = (1 × 3.14 × 10-6) / (1.7 × 10-8)
l = 1.847 × 102 m
Therefore,
l = 184.7 m