Home › ISC Class 12 › Physics › Moving Charges and Magnetism › A current loop of magnetic moment m is placed in…
A current loop of magnetic moment m is placed in a uniform field B so that m makes angle θ with B. The torque on the loop has magnitude:
Am B tan θ
Bm B cos θ
Cm B sin θ
Dm B
Answer & Solution
Correct answer: C. m B sin θ
1. The torque on a magnetic dipole is $\boldsymbol{\tau} = \mathbf{m}\times\mathbf{B}$.
2. The magnitude of a cross product is $\tau = mB\sin\theta$.
3. Here $\theta$ is the angle between m and B.
4. The torque is maximum at $\theta = 90^\circ$ and zero at $\theta = 0$, ruling out the cos θ form.
_Source: NCERT Class 12 Physics Ch 4 "Moving Charges and Magnetism", p.156_
Related questions
An electron and a proton enter a magnetic field with the same kinetic energy, perpendiculaA galvanometer is converted into an ammeter of higher range by connecting:The work done by a static magnetic force on a moving charge is:Magnetic field at a point on the axis of a circular loop, far from the loop (distance x ≫ The dimensional formula of the magnetic field B (in SI units of tesla) is:A cyclotron of magnetic field B accelerates positive charges of mass m, charge q. The cyclTorque on a magnetic dipole (current loop) of moment m placed in a uniform field B at anglTwo long parallel wires carry currents I₁ and I₂ in the SAME direction, separated by dista