Is magnetic force perpendicular to the magnetic field?

1 Answer
Nov 4, 2014

The direction of force between a magnet and an object having a magnetic moment (such as a piece of steel) is dependent on the change in density of magnetic field. In most cases the object will be attracted directly toward the magnet because the field strength is highest at the surface of the magnet.

However, the interaction of a magnetic field with a charged particle (electron or ion) is completely different. In this case, the Lorentz force is perpendicular to both the instantaneous velocity of the particle and the direction of the magnetic field.

For example, if the magnetic field is oriented along the z-axis and the instantaneous velocity of the charged particle is along the x axis, then the Lorentz force will bend the trajectory toward the y-axis such that the particle will execute circular orbits in the x,y plane around the magnetic field lines.