The force experienced by a stationary iron filing near a bar magnet will be parallel to the magnetic field line running from the north to the south pole. In light of this, I cannot make intuitive sense of the fact that the magnetic force on an object in motion is 0 if the object is moving parallel to the magnetic field.
Is the distinction simply that the object in motion is an electrical point charge and the magnet's effect on it is different than on the iron filing?

Please help. Thank you!

Question

The force experienced by a stationary iron filing near a bar magnet will be parallel to the magnetic field line running from the north to the south pole.  In light of this, I cannot make intuitive sense of the fact that the magnetic force on an object in motion is 0 if the object is moving parallel to the magnetic field.  
Is the distinction simply that the object in motion is an electrical point charge and the magnet's effect on it is different than on the iron filing?

Please help.  Thank you!

anonymous · Answer

The iron filing is made of iron, a ferromagnetic material. This means that the iron filing has magnetic domains (or groups of spinning electrons) that can realign themselves. In the presence of a magnetic field (in this case, the bar magnet), the magnetic domains realign themselves with the external magnetic field and thus, the iron filing is attracted to the bar magnet. However, the force on charged particles is different. A magnetic field exerts a force on a charged particle only if that charged particle is moving (and moving at an angle to the magnetic field - not parallel).

anonymous · Answer

The following link might help you: http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html Search for magnetic domains, ferromagnetism, and magnetic force. Hope this helps!