Explanation:
Current, \(i=\dfrac{Q}{t}=\dfrac{e}{T}=\dfrac{e}{2 \pi r / v}\)
\(\,\,\,\,\,\)\(=\dfrac{e v}{2 \pi r}\)\(\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\)
Here, \(r=\dfrac{\hbar^{2}}{m e^{2}}, v=\dfrac{e^{2}}{\hbar}, \hbar=\dfrac{h}{2 \pi}\)
Eqn. (1) becomes,
\(i = \frac{{e \times \frac{{{e^2}}}{\hbar }}}{{2\pi \frac{{{\hbar ^2}}}{{m{e^2}}}}} = \frac{{m{e^5}}}{{2\pi {\hbar ^3}}} = \frac{{4{\pi ^2}m{e^5}}}{{{h^3}}}\)