An electron(e) is revolving in a circular orbit of radius 'r' in hydrogen atom. The angular momentum of the…

An electron(e) is revolving in a circular orbit of radius 'r' in hydrogen atom. The angular momentum of the electron is (M = magnetic dipole moment associated with it and $\mathrm{m}=$ mass of electron $)$
  1. $\frac{4 \mathrm{mM}}{\mathbf{C}}$
  2. $\frac{2 m M}{e}$
  3. $\frac{3 \mathrm{Mmm}}{\mathbf{C}}$
  4. $\frac{\mathrm{mM}}{\mathrm{e}}$

Solution

The angular momentum of electron is given as $L$ $\begin{array}{l} =m v r=m(r \omega) \cdot r=m \omega r^{2} \\ \Rightarrow \omega r^{2}=\frac{L}{m} \quad \ldots(i) \end{array}$ Magnetic dipole moment, $\begin{array}{l} M=i A=\frac{e}{T} \cdot \pi r^{2}=\frac{e}{2 \pi / \omega} \cdot \pi r^{2}=\frac{e}{2} \cdot \omega r^{2} \\ \Rightarrow M=\frac{e}{2} \cdot \frac{L}{m} \text { [From Eq. (i)] } \\ \Rightarrow L=\frac{2 m M}{e} \end{array}$

Asked in: MHT CET 2020 (16 Oct Shift 1)

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