Answer:
Length of wire will be 2.45 m
Explanation:
We have given resistivity of the wire [tex]\rho =10^{-6}ohm-m[/tex]
Diameter d= 0.25 mm
So radius [tex]r=\frac{d}{2}=\frac{0.25}{2}=0.125mm=0.125\times 10^{-3}m[/tex]
Area [tex]A=\pi r^2=3.14\times (0.125\times 10^{-3})^2=4.9\times 10^{-8}m^2[/tex]
Resistance of wire = 50 ohm
We know that resistance is given by [tex]R=\frac{\rho l}{A}[/tex]
So [tex]50=\frac{10^{-6}l}{4.9\times 10^{-8}}[/tex]
[tex]l=2.45m[/tex]
So length of wire will be 2.45 m
