Question

The period of revolution of an electron revolving in $n^{th}$ orbit of $H$-atom is proportional to

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

Answer 1

Answer: (C)

As we know that time period of revolution of an electron is
$T=2\pi r/v$,
And $r\propto n^2/Z^2$ and $v\propto Z/n$
$\therefore T\propto n^3/Z^2$ and for $H$ -atom
$Z=1,T\propto n^3$