Magnetic forces and magnetic torque potential

Discussion in 'Physics' started by Skeebopstop, Nov 1, 2012.

  1. Skeebopstop

    Thread Starter Active Member

    Jan 9, 2009
    Dear All,

    I have been refreshing my magnetics over the past few days and came across what appears to be a bit of a paradox. I'm sure it has as valid explanation but I can't think of it myself so I raise the question to you.

    If the force on a magnetic moment (magnetic pole model) of a very small magnet is known to be:

    See image "Force.png".

    Therefore, if the field and magnetic moment are at 90 degrees to one and other (or there is no gradient), there is no force. Now we go to the torque model:

    See image "torque image.png" and "torque.png" for illustration/equation.

    So now imagine that the magnet shown is at 90 degrees to the illustrated field. I realize that from the torque equation, that is the point of maximum torque but how can I relate this to the original "Force.png" where it is telling me that the magnetic moments that compose the magnet should have no force on them!

    Any help in understanding the relationship of these equations would be much obliged.