A current loop in a magnetic field - Vidyadip

MCQ

A current loop in a magnetic field

A
experiences a torque whether the field is uniform or non uniform in all orientations.
B
can be in equilibrium in one orientation.
C
can be in equilibrium in two orientations,both the equilibrium states are unstable.
✓
can be in equilibrium in two orientations, one stable while the other is unstable.

✓

Answer

Correct option: D.

can be in equilibrium in two orientations, one stable while the other is unstable.

d
When a current loop is placed in a magnetic field it experiences a torque. It is given by

$\vec{\tau}=\vec{M} \times \vec{B}$

where, $\vec{M}$ is the magnetic moment of the loop and $\vec{B}$ is the magnetic field.

or $\quad \tau=M B \sin \theta$ where $\theta$ is angle between $M$ and $B$ When $\vec{M}$ and $\vec{B}$ are parallel (i.e. $\theta=0^{\circ}$ ) the equilibrium is stable and when they are antiparallel (i.e. $\theta=\pi$ ) the equilibrium is unstable.

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