Problem 3.267

In Hall effect measurements in a sodium conductor the strength of a transverse field was found to be equal to $E=5.0 \mu \mathrm{V} / \mathrm{cm}$ with a current density $j=200 \mathrm{~A} / \mathrm{cm}^{2}$ and magnetic induction $B=$ $=1.00 \mathrm{~T} .$ Find the concentration of the conduction electrons and its ratio to the total number of atoms in the given conductor.