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NEET PHYSICSMOVING CHARGES AND MAGNETISMMedium

Question

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

D

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

Step-by-Step Solution

According to the sources, a current-carrying loop with magnetic moment m\mathbf{m} in a uniform magnetic field B\mathbf{B} experiences a torque given by τ=m×B\boldsymbol{\tau} = \mathbf{m} \times \mathbf{B}, where the magnitude is τ=mBsin⁡θ\tau = mB \sin \theta . Equilibrium occurs when the net torque is zero, which happens when the magnetic moment is either parallel (θ=0∘\theta = 0^\circ) or antiparallel (θ=180∘\theta = 180^\circ) to the magnetic field .

  1. Stable Equilibrium: At θ=0∘\theta = 0^\circ, the potential energy U=−m⋅B=−mBU = -\mathbf{m} \cdot \mathbf{B} = -mB is at its minimum. In this orientation, any small displacement results in a restoring torque that brings the loop back to its original position .
  2. Unstable Equilibrium: At θ=180∘\theta = 180^\circ, the potential energy U=+mBU = +mB is at its maximum. Any small displacement from this position will cause the loop to rotate away to reach the stable state .

Thus, the loop can be in equilibrium in two orientations: one stable and one unstable.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from MOVING CHARGES AND MAGNETISM. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSMOVING CHARGES AND MAGNETISMcurrentmagnetic

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