Question

What is the resistance of a copper wire 200 ft long and
0.01 in. in diameter (T 20°C)?

Answer 1

R = 20.21 ohms

Step-by-step explanation:

Given that,

The length of the wire, l = 200 ft

The diameter of the wire, d = 0.01 in

Radius, r = 0.005 in

200 ft = 60.96 m

0.005 in = 0.000127 m

The resistivity of copper is,
`\rho=1.68* 10^(-8)\ \Omega-m`

So, the resistance of a wire is given by :

`R=\rho (l)/(A)\\\\R=\rho (l)/(\pi r^2)\\\\R=1.68* 10^(-8)* (60.96 )/(\pi * (0.000127 )^2)\\\\R=20.21\ \Omega`

So, the resistance of the copper wire is 20.21 ohms.