Question

EXAMPLE 3.33: Resistance of a metal wire of length 1 m is 26 at 20°C. If the diameter of the
is 0.7 mm, what will be the resistivity of the metal at that temperature?​

Answer 1

R=26 Ω

l=1m

d−0.3mm

r=  

2

d

​  

=  

2

0.3×10  

−3

 

​  

=0.15×10  

−3

m

A=πr  

2

=3.14×(0.15×10  

−3

)  

2

=0.071×10  

−6

m  

2

 

R=  

A

ρL

​  

 

or ρ=  

l

RA

​  

=  

1

26×0.071×10  

−6

 

​  

=1.84×10  

−6

Ωm