A metal wire has diameter of 0.25 mm and electrical resistivity of 0.8 ×10-8 Ω-m. The length of this wire required to make a resistance of 5 is [[1]] m.

A metal wire has diameter of

$0.25 mm$ and electrical resistivity of

$0.8 \times 10^{- 8} Ω - m$ . The length of this wire required to make a resistance of

$5$ is

$30.62 m$ .
Given, diameter of wire = 0.25 mm
Resistivity, ρ = 0.8 x10-8 Ω-m
Resistance, R =

$5$
We know that,

$R = l / A$
⇒

$l = AR /$ ρ
⇒

$l = \frac{π \times [\frac{0.25}{2} \times 10^{- 3}] \times 5}{0.8 \times 10^{- 8}}$
⇨

$\frac{π \times 5 \times 1.56 \times 10^{- 8}}{0.8 \times 10^{- 8}}$

$= 30.62 m$

A metal wire has diameter of $0.25 mm$ and electrical resistivity of $0.8 \times 10^{- 8} Ω - m$ . The length of this wire required to make a resistance of $5$ is [[1]] m.