Question

Calculate the resistance of 100m long copper wire. The diameter of the wire is 1mm

Answer 1

R = resistivity x length / Area

Given length = 100 m, Area = pi (0.5)^2 * 10^-6 m^2 [ here radius = diameter/2, and 1 mm = 10^-3 m]

Resistivity = 1.7 x 10^-8 ohm m

Hope you plug and get the resistance as R = 6.8/pi ohm

Answer 2

Answer:

Resistance, R = 2.13 ohms

Explanation:

It is given that,

Length of copper wire, l = 100 m

Diameter of the wire, d = 1 mm

Radius of the wire, r = 0.5 mm = 0.0005 m

Resistivity of copper wire, $\rho=1.68\times 10^{-8}\ \Omega-m$

Resistance of a wire is given by :

$R=\rho\dfrac{l}{A}$

$R=1.68\times 10^{-8}\times \dfrac{100}{\pi (0.0005)^2}$

R = 2.13 ohms

So, the resistance of the copper wire is 2.13 ohms. Hence, this is the required solution.