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An electron is moving in an orbit around the nucleus in an atom. Let $m$, b orbital magnetic moment and $L$ be angular momentum of the electron, then
PhysicsAtomic PhysicsMHT CETMHT CET 2022 (08 Aug Shift 1)
Options:
  • A $m$ and $L$ are in opposite direction perpendicular to the plane of orbit.
  • B $m$ and $L$ are in opposite direction parallel to the plane of orbit.
  • C $m$ and $L$ are in the same direction perpendicular to the plane of the orbit.
  • D $m$ and $L$ are in the same direction parallel to plane of the orbit.
Solution:
1861 Upvotes Verified Answer
The correct answer is: $m$ and $L$ are in opposite direction perpendicular to the plane of orbit.
Consider the following diagram:


The magnetic moment due to the movement of electron is given by,
$\vec{m}=i \vec{A}$
The direction of magnetic moment will be into the paper, using the right hand curl rule.
The angular momentum of electron is given by,
$\vec{L}=\vec{r} \times \vec{p}$
We know $\vec{p}$ is along $\vec{u}$ as shown in the figure, then
$\vec{L}=m \vec{r} \times \vec{u}$
The direction of angular momentum of the electron will be out of the plane of the paper.

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