Question

An electric motor uses 180m of copper conductor with a cross sectional area of 0.26 cm². Find the resistance of the electric motor. The resistivity of copper is 1.72x10^-8 ohm meter.

Answer 1

We can find the resistance as follows:

$$R=\dfrac{\rho L}{A},$$ $$R=\dfrac{1.72\cdot10^{-8}\ \Omega\cdot m\cdot10\ m}{0.26\ cm^2\cdot(\dfrac{1\ m}{100\ cm})^2}=0.12\ \Omega.$$