Question

3.The resistance of a 15-m length of iron wire whose cross sectional area is 0.5 mm^2 is found to be 3.6 ohms. What is the resistivity of Iron?

Answer 1

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Given that,

Length = L = 15m

Area of Cross - Section = A = 0.5mm² = 0.5×10⁻⁶ m²

Resistance = R = 3.6Ω

Resistivity = ρ = ?

R = ρL/A

ρ = RA/L

ρ = 3.6×0.5×10⁻⁶/15

ρ = 1.2×10⁻⁷ ohm m⁻¹