Question

Calculate the resistivity of a wire of length 1m and 0.01cm and resistance 20ohm

Answer 1

As we know,

R = ρ L/A

r = 0.01 cm = 1×10⁻⁴ m
A = πr² = 3.14×(1×10⁻⁴ )m² = 3.14×10⁻⁸ m²

now, ρ = RA/L
=(20×3.14×10⁻⁸ )/1
=6.28×10⁻⁷ ohm-m