Question

what is the resistance of a 12m long wire having radius( 2*10 to the power - 4) and resistivity (3.14*10 to the power - 8)ohmM

Answer 1

R = ρl/A

Where R = Resistance in Ohms, Ω, ρ = Resistivity in Ωm, l = Length in m.

Area in m²

ρ = Resistivity = 3.14 * 10⁻⁸ Ωm,  Length l = 12m, 

Area = πr² = π* (2*10⁻⁴)² m² ≈ 3.14 * (2*10⁻⁴)² m²


R = ρl/A

    ≈ 3.14 * 10⁻⁸ * 12 / (3.14 * (2*10⁻⁴)²)

     ≈ 3

Resistance, R ≈ 3 Ω