Question

calculate the resistance of 1 km long copper wire of radius 1mm . resistivity of copper is 1.72×10-⁸​

Answer 1

Answer:

Resistivity of copper is 1.72 xx 10^-8 Omega m. If R is the resistance of the given wire, then R=ρlA=(1.72×10-8Ωm)×(1000m)3. 14×10-6m2=5.48Ω.

Answer 2

Answer:

The resistance of 1 km long copper wire of radius 1mm is 5.48 Ω.

Explanation:

In an electrical circuit, resistance is a measure of the resistance to current flow. The unit of resistance is ohms.

Resistance R = $\frac{PL}{A}$

Where,

P = resistivity = $1.72*10^{-8}$ Ωm

L = length = 1 km = 1000 m

A = area of cross section

Given that radius r = 1 mm = $1*10^{-3}$ m

Area of cross section of the wire = π$r^{2}$

                                                       = 3.14 × $(1*10^{-3})^{2}$

                                                       = $3.14*10^{-6}$ $m^{2}$

Now resistance R = $\frac{PL}{A}$

                             = $\frac{1.72*10^{-8} *1000}{3.14*10^{-6} }$

                             = 5.48 Ω

Therefore, the resistance of 1 km long copper wire of radius 1mm is 5.48 Ω.