Question

The energy of an electron in excited hydrogen atom is $-3.4eV$. Then according to Bohr's theory the angular momentum of the electron in $Js$ is

• A. $2.11\times {10}^{-34}$
• B. $3\times {10}^{-34}$
• C. $4\times {10}^{-34}$
• D. $0.5\times {10}^{-34}$

Answer 1

The correct option is A $2.11\times {10}^{-34}$

Energy of a Hydrogen atom $E=\frac{-13.6}{n^2}$
Given $E=-3.4=\frac{-13.6}{n^2}$
$\Rightarrow n=2$
Angular momentum $L=\frac{nh}{2\pi }$
$n=2\Rightarrow \text{Angular momentum}{L}_2=\frac{2h}{2\pi }=\frac{h}{\pi }=\frac{6.62\times {10}^{-34}}{3.14}$

$=2.11\times {10}^{-34}\text{J-sec}$