Problem 6.80

An electron is located in a unidimensional square potential well with infinitely high walls. The width of the well equal to \(l\) is such that the energy levels are very dense. Find the density of energy levels \(d N / d E,\) i.e. their number per unit energy interval, as a function of \(E .\) Calculate \(d N / d E\) for \(E=1.0 \mathrm{eV}\) if \(l=1.0 \mathrm{~cm}\).