Question

What is Lorentz number? The thermal and electrical conductivities of Cu at 20^oC are 390 Wm^-1K^-1 and

5.87x10⁷W^-1m^-1 respectively. Calculate Lorentz number.​​

Answer 1

The Lorentz number is given by

$$L=\frac{\kappa}{\sigma T}$$ $$L=\rm\frac{290\: Wm^{-1}K^{-1}}{5.87\times 10^{7}\: \Omega ^{-1}m^{-1}\times 293\: K}=1.69\times 10^{-8}\: W\Omega K^{-2}$$