Q84 / 120 · VITEEE 2015 · Physics
The angular momentum of an electron in Bohr's hydrogen atom whose energy is $-3.4 \mathrm{eV}$, is
- A$\frac{5 h}{2 \pi}$
- B$\frac{h}{2 \pi}$
- Correct answerC$\frac{h}{\pi}$
- D$\frac{2 h}{3 \pi}$
Solution
Energy of electron in nth orbit of hydrogen atom
$\begin{aligned}
& E_{n}=-\frac{13.6}{n^{2}} \mathrm{eV} \\
\Rightarrow & 3.4=-\frac{13.6}{n^{2}} \Rightarrow n^{2}=4
\end{aligned}$
or, $\mathrm{n}=2$
Angular momentum of electron
$\mathrm{L}=\frac{\mathrm{nh}}{2 \pi}=\frac{2 \mathrm{~h}}{2 \pi}=\frac{\mathrm{h}}{\pi}$
Hence, the correct answer is option: 'C'.