Question

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

Answer 1

given-- length(L)=1m
            radius(r)=0.1mm=10^-4[since diameter is 0.2mm]["^" is used to show                                                                                                 degree of power]
            resistance(R)=10 ohm

area = 3.14 x r x r =3.14 x 10^-4 x 10^-4 = 3.14 x 10^-8 m^2
Resistivity = ( R x area)/L
                 = (10 x 3.14 x 10^-8)/1
                 = 3.14 x 10^-7 ohm

PS ---- i think this is the answer but i too am a beginner and am just going by the formula given in my book. let me know if this is the correct answer.

Answer 2

HI there !!

Length = l = 1 m

Diameter = 0.2mm

Radius = r = 0.1 mm = 0.0001 m

Area = A =πr² = 3.14 × 0.0001 × 0.0001 = 3.14×10⁻⁸ m²

Resistance = R = 10 Ω

Resistivity = ρ = RA / l
= 10 ×  3.14×10⁻⁸ / 1
= 31.4×10⁻⁸ Ω m