Question

The angular momentum of an electron in Bohr’s hydrogen atom whose energy is $-3.4\, eV$, is

• A. $\frac{5h}{2 \pi } $
• B. $\frac{h}{2 \pi } $
• C. $\frac{h}{\pi } $
• D. $\frac{2h}{3\pi } $

Answer 1

Answer: (C)

Energy of electron in nth orbit of hydrogen atom
$E_{n} = - \frac{13.6}{n^{2}} eV $
$ \Rightarrow 3.4 = - \frac{13.6}{n^{2} } $
$\Rightarrow n^{2} = 4 $
or, $n =2$
Angular momentum of electron
$ L = \frac{nh}{2\pi} = \frac{2h}{2\pi} = \frac{h}{\pi} $