Question

A wire is 1m long ,0.2mm in diameter and has resistance of 10 ohm .calculate its resistivity

Answer 1

Resistance = resistivity*l/A
Resistance*A/l = resistivity
10*3.14(0.0001*0.0001)/1 = resistivity
10*3.14*1^-8
31.4*1^-8 = resistivity

Answer 2

HI there !!

Length  = l = 1 m

Diameter = 0.2mm 

Radius = r = 0.1 mm = 0.001 m

Area = A =πr² = 3.14 × 0.001 × 0.001 = 0.00000314 m²

Resistance = R = 10 Ω

Resistivity = ρ  = RA / l
                        = 10 × 0.00000314 / 1
                        = 0.0000314 Ω m