Question

A 7.8-meter long copper wire has a diameter of 3.3x10exp(- ) 2 m. Determine the resistance of the wire.

Answer 1

In order to calculate the wire resistance, we can use the formula below:

`R=(p\cdot L)/(A)`

Where p is the resistivity, L is the length and A is the cross-section area.

For copper, we have p = 1.72 * 10^-8.

Then, using L = 7.8 m and A = pi*r² (area of a circle), we have:

`\begin{gathered} R=(1.72\cdot10^(-8)\cdot7.8)/(\pi\cdot((3.3)/(2)\cdot10^(-2))^2) \\ R=(13.416\cdot10^(-8))/(3.1416\cdot2.7225\cdot10^(-4)) \\ R=(13.416\cdot10^(-8))/(8.553\cdot10^(-4)) \\ R=1.57\cdot10^(-4) \end{gathered}`

Therefore the wire resistance is 1.57 * 10^-4 ohms.