- When a bar magnet is placed in a uniform magnetic field, the north and south poles of the magnet experience opposite forces due to the interaction between the magnetic field and the magnetic field of the bar magnet.
- The forces acting on each pole of the magnet cause a moment or torque to be exerted on the bar magnet, which tends to rotate the bar magnet so that its north pole is aligned with the direction of the magnetic field.
The formula for the moment of a couple acting on a bar magnet placed in a uniform magnetic field is given by:
τ = μ * B * L * sin(θ)
Where:
- τ is the moment of the couple or torque,
- μ is the permeability of the medium,
- B is the magnetic induction or magnetic field strength in tesla (T),
- L is the length of the bar magnet, and
- θ is the angle between the bar magnet and the direction of the magnetic field.