Question

In a hydrogen atom, electron revolves in a circular orbit of radius $0.53\stackrel{\circ }{A}$ with a velocity of $2.2\times {10}^{6}m{s}^{-1}$. If the mass of electron is $9.0\times {10}^{-31}kg$, find its angular momentum.

• A. $05\times {10}^{-34}kg{m}^2{s}^{-1}$.
• B. $1.05\times {10}^{-34}kg{m}^2{s}^{-1}$.
• C. $2.05\times {10}^{-34}kg{m}^2{s}^{-1}$.
• D. $3.05\times {10}^{-34}kg{m}^2{s}^{-1}$.

Answer 1

The correct option is B $1.05\times {10}^{-34}kg{m}^2{s}^{-1}$.

$\text{Given-}\ast \text{Radius}r=0.53A^{\circ }\ast \text{velocity}v=2.2\times {10}^{6}m/s$

$\ast \text{mass}m=9\times {10}^{-31}kg$

$\text{Orbital an gular momentum}$ =m v r

$\begin{array}{cc}mvr& =9\times {10}^{-31}kg\times 2.2\times {10}^{6}m/s\times 0.53\times {10}^{-10}m\\ & =1.05\times {10}^{-34}kg{m}^2/s\end{array}$