Question

A copper cable is 1.2 km long and has a cross-sectional area of 5 mm^2. Find its resistance at 80°C if at 20°C the resistivity of copper is 0.02*10^-6ohm m and its temperature coefficient of resistance is 0.004/°C

Answer 1

Step-by-step explanation:

Equation for resistity

`p(t)= p(0) * (1 + a * (change \: in \: temp))`

`= 0.02 * {10}^( - 6) * (1 + 0.004 * 60)`

`= 2.48 * {10}^( - 8) ohm \: m`

`r = (p * l) / a`

`= (2.48 * {10}^( - 8) * 1200) / \: 5 * {10}^( - 6)`

`= 5.952 \: ohms`