Question

Calculate the resistance of a wire whose a length is 20 m and the cross-sectional radius is 2mm, the resistivity is 6.28 x 10 ohm m.​

Answer 1

Given :

l =20 m

r = 2mm = 0.002

ρ= 6.28 × $10 ^{ -8$ Ωm

To find :

resistance  = R = ?

Explanation:

We know that the cross-sectional area of the wire is the area of a circle.

A = π$\displaystyle r^2$

   = 3.24 × 0.002 × 0.002

A = 12.56 × $\displaystyle 10^{-6$ m

A = 12.56 μm

Now we have to calculate resistance :

R =  ρ $\displaystyle \frac{l}{A}$

  = $\displaystyle { (6.28 \times 10^{-8} )\times \frac{20}{(12.56 \times 10^{-6})}$

  = 10 × $\displaysyle {10^-2$

R = 0.1 Ω