A bar magnet of magnetic moment ⃗m is placed in uniform magnetic field ⃗B such that ⃗m∥⃗B. In this position, the torque and force acting on it are and respectively.

Question

Accepted Answer

(1) 0, 0. Idea: answer the two halves separately -- first the twist, then the pull. Torque: τ⃗=⃗m×⃗B, of magnitude mB sin θ. Here ⃗m is parallel to ⃗B, so θ=0, sin 0=0 and τ=0. The magnet is already in its equilibrium orientation. Force: in a uniform field the force on the north pole and the force on the south pole are equal in size and opposite in direction, whatever the orientation, so they cancel and the net force is 0. A net force on a magnet needs the field to vary from place to place, and a uniform field does not. So both the torque and the force are zero.

A bar magnet of magnetic moment ⃗m is placed in uniform magnetic field ⃗B such that ⃗m∥⃗B. In this position, the torque and force acting on it are and respectively.

Step-by-step solution

Why the other options are wrong

A bar magnet of magnetic moment ⃗m is placed in uniform magnetic field ⃗B such that ⃗m∥⃗B. In this position, the torque and force acting on it are ______ and ______ respectively.

Step-by-step solution

Why the other options are wrong

A bar magnet of magnetic moment ⃗m is placed in uniform magnetic field ⃗B such that ⃗m∥⃗B. In this position, the torque and force acting on it are and respectively.