Question

The length of conducting wire is 80 cm and its radius is 0.8 mm. If it's resistance is 80 Ω. What is the resistivity of material ?​

Answer 1

Length of the conducting wire(l) =80 cm

                                                     =0.8 m

radius(r)=0.8× $10^{-3}$m

resistance(R)= 80 Ω

area of the wire(a)=πr²=π×0.8×0.8×$10^{-3}$×$10^{-3}$

                                =3.14×0.8×0.8×$10^{-3}$×$10^{-3}$

                                =2.0096×$10^{-6}$ m²

  as we know that,

                              R=  ρ×(l/a)

                              ρ=(R×a)/l

                              ρ=(80×2.0096×$10^{-6}$)/0.8

                                =2.096×$10^{-5}$ Ωm