The force on a north pole, is parallel to the field . Does it contradict our earlier knowledge that a magnetic field can expert forces only perpendicular to itself.

Yes, The question statement contradicts our earlier knowledge. But this confusion can be rectified by understanding the above equation.


In the equation, , m represents the ‘Magnetic charge’, represents the Magnetic force and represents the magnetic field.


A magnetic charge can be understood by doing the analogy with an electric charge.


A magnetic field, exert a force on the magnetic charge, which is parallel to the Magnetic field itself and is proportional to the magnitude of magnetic charge and Magnetic field, analogous to electric field exerting force on an electric charge.


But, from Lorentz law, we know that Magnetic force is perpendicular to magnetic field.



Where q represents an electric charge, v represents the velocity of movement. By this relation, the magnetic force is perpendicular to the magnetic field.


In this law, a moving electric charge is used to define the magnetic force, which is not used in the former equation. So the above cases cannot be compared directly.


The non-existence of a monopole in magnetism makes the former equation obsolete and hence Lorentz equation is widely used for practical cases.


Hence, even though the two concepts seem to contradict while comparing the orientations of magnetic field and magnetic force, they are not effectively the same equations.


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