Question

a wire is 10 metre long 0.2 mm in diameter and has a resistance of 10 ohm calculate the resistivity of its material​

Answer 1

Given,

l=0.1m=1000mm

d=0.2mm∴radius(r)=  

2

0.2

​  

=0.1mm

R=10Ω

To find,

Resistivity(ρ)

ρ=R  

l

A

​  

 

where,

R= Resistance

l= Length of wire

A= Cross sectional area of wire

Cross sectional area of cylinder (A)=Πr  

2

 

⇒A=π×(0.1)  

2

 

⇒A=0.0314mm  

2

 

∴ρ=10(  

1000

0.0341

​  

)

⇒ρ=0.000314Ω−mm

⇒ρ≃3.14×10  

−7

Ω−m

So, the resistivity of the material is equal to 3.14×10  

−7

Ω−m

Hope this helped :)