Question

Frequency of revolution of an electron revolving in nth orbit of H-atom is proportional to

• A. $nindependentofn$
• B. $\frac{1}{n^2}$
• C. $\frac{1}{n^3}$
• D. n

Answer 1

Answer: (C)

Time period of revolution, $T=\frac{2\pi r}{v}$
Frequency of revolution , $f=\frac{v}{2\pi r}$
$v\propto \frac{1}{n}<br/>r\propto n^2$ and hence $f\propto \frac{1}{n^3}$