An electron revolves around the nucleus in a circular path with angular momentum $\overrightarrow{\mathrm{L}} . \mathrm{A}$ uniform magnetic field $\overrightarrow{\mathrm{B}}$ is applied perpendicular to the plane of its orbit. If the electron experiences a torque $\overrightarrow{\mathrm{T}}$, then

• A

  $\overrightarrow{\mathrm{T}} \| \overrightarrow{\mathrm{L}}$
• B

  $\overrightarrow{\mathrm{T}}$ is anti-parallel to $\overrightarrow{\mathrm{L}}$
• Correct answer
  C

  $\overrightarrow{\mathrm{T}} \cdot \overrightarrow{\mathrm{L}}=0$
• D

  Angle between $\vec{T}$ and $\vec{L}$ is $45^{\circ}$

Solution

$\vec{\tau}=0 \Rightarrow \vec{\tau} \cdot \vec{L}=0$

Hence, the correct answer is option: 'C'.